Make better use of i18n (#20096)

* Prototyping

* Start work on creating offsets

* Modify tests

* Start prototyping with actual MPH

* Twiddle around

* Twiddle around comments

* Convert templates

* Fix external languages

* Fix latest translation

* Fix some test

* Tidy up code

* Use simple map

* go mod tidy

* Move back to data structure

- Uses less memory by creating for each language a map.

* Apply suggestions from code review

Co-authored-by: delvh <dev.lh@web.de>

* Add some comments

* Fix tests

* Try to fix tests

* Use en-US as defacto fallback

* Use correct slices

* refactor (#4)

* Remove TryTr, add log for missing translation key

* Refactor i18n

- Separate dev and production locale stores.
- Allow for live-reloading in dev mode.

Co-authored-by: zeripath <art27@cantab.net>

* Fix live-reloading & check for errors

* Make linter happy

* live-reload with periodic check (#5)

* Fix tests

Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: 6543 <6543@obermui.de>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>

templates/repo/settings/lfs.tmpl

@@ -23,7 +23,7 @@
 							</span>
 						</td>
 						<td>{{FileSize .Size}}</td>
-						<td>{{TimeSince .CreatedUnix.AsTime $.i18n.Lang}}</td>
+						<td>{{TimeSince .CreatedUnix.AsTime $.i18n}}</td>
 						<td class="right aligned">
 							<a class="ui primary show-panel button" href="{{$.Link}}/find?oid={{.Oid}}&size={{.Size}}">{{$.i18n.Tr "repo.settings.lfs_findcommits"}}</a>
 							<button class="ui basic show-modal icon button" data-modal="#delete-{{.Oid}}">

templates/repo/settings/lfs_file_find.tmpl

@@ -37,7 +37,7 @@
 								{{$.i18n.Tr "repo.diff.commit"}}
 								<a class="ui primary sha label" href="{{$.RepoLink}}/commit/{{.SHA}}">{{ShortSha .SHA}}</a>
 							</td>
-							<td>{{TimeSince .When $.i18n.Lang}}</td>
+							<td>{{TimeSince .When $.i18n}}</td>
 						</tr>
 					{{else}}
 						<tr>

templates/repo/settings/lfs_locks.tmpl

@@ -39,7 +39,7 @@
 									{{$.Owner.DisplayName}}
 								</a>
 							</td>
-							<td>{{TimeSince .Created $.i18n.Lang}}</td>
+							<td>{{TimeSince .Created $.i18n}}</td>
 							<td class="right aligned">
 								<form action="{{$.LFSFilesLink}}/locks/{{$lock.ID}}/unlock" method="POST">
 									{{$.CsrfTokenHtml}}