Test renderReadmeFile (#23185)

Add test coverage to the important features of
[`routers.web.repo.renderReadmeFile`](067b0c2664/routers/web/repo/view.go (L273));
namely that:

- it can handle looking in docs/, .gitea/, and .github/
- it can handle choosing between multiple competing READMEs
- it prefers the localized README to the markdown README to the
plaintext README
- it can handle broken symlinks when processing all the options
- it uses the name of the symlink, not the name of the target of the
symlink

tests/gitea-repositories-meta/user2/readme-test.git/HEAD

@@ -0,0 +1 @@
+ref: refs/heads/master

tests/gitea-repositories-meta/user2/readme-test.git/config

@@ -0,0 +1,4 @@
+[core]
+	repositoryformatversion = 0
+	filemode = true
+	bare = true

tests/gitea-repositories-meta/user2/readme-test.git/info/exclude

@@ -0,0 +1,6 @@
+# git ls-files --others --exclude-from=.git/info/exclude
+# Lines that start with '#' are comments.
+# For a project mostly in C, the following would be a good set of
+# exclude patterns (uncomment them if you want to use them):
+# *.[oa]
+# *~

tests/gitea-repositories-meta/user2/readme-test.git/info/refs

@@ -0,0 +1,21 @@
+ea9ef877d1d88af76682d8798418081264f10cfc	refs/heads/fallbacks
+0d4c14db927c9ffba01fa7e126cc748b5c02c01e	refs/heads/fallbacks2
+c66d5b07c2063d3268707f22226c708b589574ef	refs/heads/fallbacks3
+89f8426e9eb5eff35c09b3565836c8f8e15d0ce9	refs/heads/fallbacks4
+b0e902496eae435ad03c92a5d479f916ef2d4893	refs/heads/fallbacks5
+84a5500b5cc040b11daf53fc42c542a99589dc76	refs/heads/fallbacks6
+cf406a96e416d7de5c4c1bbfffdd672300c822bf	refs/heads/fallbacks7
+0d6ac644b969e9199915a492da9dba08c179fd23	refs/heads/fallbacks8
+5038febc0c57215beb3748d7ae4091a25a4acc93	refs/heads/fallbacks9
+9134e1f178ca4cccf1a197142646f2d7627e8cd5	refs/heads/i18n
+744d2441e55bc0010d6b340d303f0106a627ad29	refs/heads/master
+3c492566170b057e962c025515ab38bbd7444077	refs/heads/plain
+3882d6373a0882a6739b3cd9b24d21c630621234	refs/heads/sp-ace
+bf5ed898252eaa50dcc01108ed4417c3ea98a294	refs/heads/special-subdir-.gitea
+c03543573ab088ce1cf7090a387d2be621426234	refs/heads/special-subdir-.github
+e75957ad9b7e6ed16dda183529ec283db0bbc5fe	refs/heads/special-subdir-docs
+46f5d5ab33d701642e08c713fab42af89fdd4fea	refs/heads/special-subdir-nested
+9c0f872256b839c2b97ec22fd348d87b14045513	refs/heads/subdir
+d7a854fff61e45b98234d7aa79ecbcb1619cd3dd	refs/heads/symlink
+30b9c0ed4b1039dbd99f3fb537b84ca507e0549d	refs/heads/symlink-loop
+41489b7be5c2244d2b7b524dcb31caf3bd1f9ccc	refs/heads/txt

tests/gitea-repositories-meta/user2/readme-test.git/objects/21/470f9b3e8ff24e0fa083d2dbc447f4c3401355

@@ -0,0 +1,2 @@
+x
<01><>;<0E>0@<40>s
+_<EFBFBD>*N<><4E>H<08><>1q
<01>u(<28>?<3F>t<EFBFBD><74>T<EFBFBD>0<><30>==<3D><><EFBFBD>Q<EFBFBD><05>+<2B>*4<><34>d<EFBFBD><64>h<EFBFBD>S<EFBFBD>η.z<><7A><EFBFBD><0E>͙Z3<5A><33>c
t<><74>0'<27>As<41>5h<08>zL<7A>=D<><44>B<EFBFBD>\cx-ݴ<><DDB4>!O<><4F><EFBFBD><EFBFBD><EFBFBD><02>q<EFBFBD><71><EFBFBD><EFBFBD><EFBFBD><<3C><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>	0<>T<EFBFBD>装<EFBFBD><E8A385><EFBFBD>5<EFBFBD>=-<2D><><EFBFBD><7F><EFBFBD>U s<>7,O<>
#<23>M<EFBFBD>

tests/gitea-repositories-meta/user2/readme-test.git/objects/3b/23d7f1a9cb904cb46f5f2272bfa5ed5f871fb9

@@ -0,0 +1 @@
+x
<01><>M<0E> <10>aל<61><0B>0&Ƹs<C6B8><73>ئ<>'<27>.<2E><><EFBFBD>x<02><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4]<5D><1A><>.)<29>D<EFBFBD><44>Q<EFBFBD>|@b6Xbd<62><64>}<7D>2+b<>%<25>T<> <1F>I>g<>	2<>7Q<37><51><EFBFBD>. (c<><63><EFBFBD><EFBFBD><EFBFBD>"o<1D><><EFBFBD>n<EFBFBD>M<EFBFBD><<3C>[6<>_^橼<>Z<1A><>T<07><>U<EFBFBD><19> <20><><EFBFBD>n<EFBFBD><6E>

tests/gitea-repositories-meta/user2/readme-test.git/objects/60/ea618ae7d4ecbe9c1962591c7da1b05bb1a5c8

@@ -0,0 +1,3 @@
+x
<01><>;<0E>0@<40>s
+_<EFBFBD>*N뤕bcc<63><02><>Њ<EFBFBD>Tҁ<54>S!N<><4E><EFBFBD><EFBFBD><EFBFBD>d<1E>><3E><><EFBFBD>!<21><><10>քLu<>Ul<55>#q<><71><EFBFBD><EFBFBD>l<EFBFBD>Q<EFBFBD>,<2C>ꔡ<EFBFBD><EA94A1>lCBn$6<><36>X<EFBFBD>Dɹ<44>bbҖR0<><30><EFBFBD><EFBFBD><EFBFBD>y<EFBFBD>[/O<>n<EFBFBD><6E><EFBFBD>
+<EFBFBD>i<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2<0F>1<0F><>Ї@<40>e<EFBFBD>p<EFBFBD>d<EFBFBD><64><EFBFBD>iޭ<69>殯<0C><>!<21><<3C><07><>N<EFBFBD>

tests/gitea-repositories-meta/user2/readme-test.git/objects/e3/a6fd8fe49e323ee10017f72b777a53fbd8076f

@@ -0,0 +1,3 @@
+x
<01><>M
+1<0C>a<EFBFBD>=E.<2E><>m<EFBFBD><6D> <20>Νwh<77><68><EFBFBD><EFBFBD>#<23>"<22><>A<<3C><>g<EFBFBD>~|eǾ<>#<23>jU:<3A><><EFBFBD><05>$%<25>9o<39><6F>{<7B>9F	<09>գQdsOU<4F><06>H<1C><>rA<72>(<28>=<3D>x<EFBFBD><78>E<EFBFBD><45><EFBFBD>$nkҳ]<5D>
+<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>\ҫV<D2AB>M7<><0F>yx<79>mؔ<6D><07>1<06>-<2D>1 <20><>}ږ<><DA96>

tests/gitea-repositories-meta/user2/readme-test.git/objects/info/packs

@@ -0,0 +1,2 @@
+P pack-8933bd634b76f8154310cccb52537a0195e43166.pack
+

tests/gitea-repositories-meta/user2/readme-test.git/packed-refs

@@ -0,0 +1,22 @@
+# pack-refs with: peeled fully-peeled sorted 
+ea9ef877d1d88af76682d8798418081264f10cfc refs/heads/fallbacks
+0d4c14db927c9ffba01fa7e126cc748b5c02c01e refs/heads/fallbacks2
+c66d5b07c2063d3268707f22226c708b589574ef refs/heads/fallbacks3
+89f8426e9eb5eff35c09b3565836c8f8e15d0ce9 refs/heads/fallbacks4
+b0e902496eae435ad03c92a5d479f916ef2d4893 refs/heads/fallbacks5
+84a5500b5cc040b11daf53fc42c542a99589dc76 refs/heads/fallbacks6
+cf406a96e416d7de5c4c1bbfffdd672300c822bf refs/heads/fallbacks7
+0d6ac644b969e9199915a492da9dba08c179fd23 refs/heads/fallbacks8
+5038febc0c57215beb3748d7ae4091a25a4acc93 refs/heads/fallbacks9
+9134e1f178ca4cccf1a197142646f2d7627e8cd5 refs/heads/i18n
+744d2441e55bc0010d6b340d303f0106a627ad29 refs/heads/master
+3c492566170b057e962c025515ab38bbd7444077 refs/heads/plain
+3882d6373a0882a6739b3cd9b24d21c630621234 refs/heads/sp-ace
+bf5ed898252eaa50dcc01108ed4417c3ea98a294 refs/heads/special-subdir-.gitea
+c03543573ab088ce1cf7090a387d2be621426234 refs/heads/special-subdir-.github
+e75957ad9b7e6ed16dda183529ec283db0bbc5fe refs/heads/special-subdir-docs
+46f5d5ab33d701642e08c713fab42af89fdd4fea refs/heads/special-subdir-nested
+9c0f872256b839c2b97ec22fd348d87b14045513 refs/heads/subdir
+d7a854fff61e45b98234d7aa79ecbcb1619cd3dd refs/heads/symlink
+30b9c0ed4b1039dbd99f3fb537b84ca507e0549d refs/heads/symlink-loop
+41489b7be5c2244d2b7b524dcb31caf3bd1f9ccc refs/heads/txt

tests/gitea-repositories-meta/user2/readme-test.git/refs/heads/fallbacks-broken-symlinks

@@ -0,0 +1 @@
+fe495ea336f079ef2bed68648d0ba9a37cdbd4aa