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/user/settings/organization.tmpl

@@ -4,10 +4,10 @@
 	<div class="ui container">
 		{{template "base/alert" .}}
 		<h4 class="ui top attached header">
-			{{.i18n.Tr "settings.orgs"}}
+			{{.locale.Tr "settings.orgs"}}
 			{{if .SignedUser.CanCreateOrganization}}
 			<div class="ui right">
-				<a class="ui primary tiny button" href="{{AppSubUrl}}/org/create">{{.i18n.Tr "admin.orgs.new_orga"}}</a>
+				<a class="ui primary tiny button" href="{{AppSubUrl}}/org/create">{{.locale.Tr "admin.orgs.new_orga"}}</a>
 			</div>
 			{{end}}
 		</h4>
@@ -19,7 +19,7 @@
 						<div class="right floated content">
 							<form method="post" action="{{.OrganisationLink}}/members/action/leave">
 								{{$.CsrfTokenHtml}}
-								<button type="submit" class="ui primary small button" name="uid" value="{{.ID}}">{{$.i18n.Tr "org.members.leave"}}</button>
+								<button type="submit" class="ui primary small button" name="uid" value="{{.ID}}">{{$.locale.Tr "org.members.leave"}}</button>
 							</form>
 						</div>
 						{{avatar . 28 "mini"}}
@@ -31,7 +31,7 @@
 				</div>
 				{{template "base/paginate" .}}
 			{{else}}
-				{{.i18n.Tr "settings.orgs_none"}}
+				{{.locale.Tr "settings.orgs_none"}}
 			{{end}}
 		</div>
 	</div>