Restrict permission check on repositories and fix some problems (#5314)

* fix units permission problems

* fix some bugs and merge LoadUnits to repoAssignment

* refactor permission struct and add some copyright heads

* remove unused codes

* fix routes units check

* improve permission check

* add unit tests for permission

* fix typo

* fix tests

* fix some routes

* fix api permission check

* improve permission check

* fix some permission check

* fix tests

* fix tests

* improve some permission check

* fix some permission check

* refactor AccessLevel

* fix bug

* fix tests

* fix tests

* fix tests

* fix AccessLevel

* rename CanAccess

* fix tests

* fix comment

* fix bug

* add missing unit for test repos

* fix bug

* rename some functions

* fix routes check

templates/repo/settings/options.tmpl

@@ -266,7 +266,7 @@
 		</div>
 		{{end}}
 
-		{{if .IsRepositoryOwner}}
+		{{if .Permission.IsOwner}}
 		<h4 class="ui top attached warning header">
 			{{.i18n.Tr "repo.settings.danger_zone"}}
 		</h4>
@@ -294,7 +294,7 @@
 				</div>
 			</div>
 
-			{{if .Repository.UnitEnabled $.UnitTypeWiki}}
+			{{if .Permission.CanRead $.UnitTypeWiki}}
 				<div class="ui divider"></div>
 
 				<div class="item">
@@ -324,7 +324,7 @@
 	</div>
 </div>
 
-{{if .IsRepositoryOwner}}
+{{if .Permission.IsOwner}}
 	{{if .Repository.IsMirror}}
 	<div class="ui small modal" id="convert-repo-modal">
 		<div class="header">