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/shared/issuelist.tmpl

@@ -51,7 +51,7 @@
 							#{{.Index}}
 						{{end}}
 					</a>
-					{{ $timeStr := TimeSinceUnix .GetLastEventTimestamp $.i18n.Lang }}
+					{{ $timeStr := TimeSinceUnix .GetLastEventTimestamp $.i18n }}
 					{{if .OriginalAuthor }}
 						{{$.i18n.Tr .GetLastEventLabelFake $timeStr (.OriginalAuthor|Escape) | Safe}}
 					{{else if gt .Poster.ID 0}}

templates/shared/searchbottom.tmpl

@@ -6,7 +6,7 @@
 		</div>
 		<div class="mr-4">
 			{{if not .result.UpdatedUnix.IsZero}}
-					<span class="ui grey text">{{.root.i18n.Tr "explore.code_last_indexed_at" (TimeSinceUnix .result.UpdatedUnix .root.i18n.Lang) | Safe}}</span>
+					<span class="ui grey text">{{.root.i18n.Tr "explore.code_last_indexed_at" (TimeSinceUnix .result.UpdatedUnix .root.i18n) | Safe}}</span>
 			{{end}}
 		</div>
 </div>