Refactor i18n to locale (#20153)

* Refactor `i18n` to `locale`

- Currently we're using the `i18n` variable naming for the `locale`
struct. This contains locale's specific information and cannot be used
for general i18n purpose, therefore refactoring it to `locale` makes
more sense.
- Ref: https://github.com/go-gitea/gitea/pull/20096#discussion_r906699200

* Update routers/install/install.go

templates/repo/settings/lfs_file_find.tmpl

@@ -6,7 +6,7 @@
 		{{template "base/alert" .}}
 		<div class="tab-size-8 non-diff-file-content">
 			<h4 class="ui top attached header">
-				<a href="{{.LFSFilesLink}}">{{.i18n.Tr "repo.settings.lfs"}}</a> / <span class="truncate sha">{{.Oid}}</span>
+				<a href="{{.LFSFilesLink}}">{{.locale.Tr "repo.settings.lfs"}}</a> / <span class="truncate sha">{{.Oid}}</span>
 			</h4>
 			<table id="lfs-files-find-table" class="ui attached segment single line table">
 				<tbody>
@@ -28,20 +28,20 @@
 							</td>
 							<td>
 								{{if .ParentHashes}}
-									{{$.i18n.Tr "repo.diff.parent"}}
+									{{$.locale.Tr "repo.diff.parent"}}
 									{{range .ParentHashes}}
 										<a class="ui primary sha label" href="{{$.RepoLink}}/commit/{{.String}}">{{ShortSha .String}}</a>
 									{{end}}
 								{{end}}
 								<div class="mobile-only"></div>
-								{{$.i18n.Tr "repo.diff.commit"}}
+								{{$.locale.Tr "repo.diff.commit"}}
 								<a class="ui primary sha label" href="{{$.RepoLink}}/commit/{{.SHA}}">{{ShortSha .SHA}}</a>
 							</td>
-							<td>{{TimeSince .When $.i18n}}</td>
+							<td>{{TimeSince .When $.locale}}</td>
 						</tr>
 					{{else}}
 						<tr>
-							<td colspan="5">{{.i18n.Tr "repo.settings.lfs_lfs_file_no_commits"}}</td>
+							<td colspan="5">{{.locale.Tr "repo.settings.lfs_lfs_file_no_commits"}}</td>
 						</tr>
 					{{end}}
 				</tbody>