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/security/openid.tmpl

@@ -1,16 +1,16 @@
 <h4 class="ui top attached header">
-	{{.i18n.Tr "settings.manage_openid"}}
+	{{.locale.Tr "settings.manage_openid"}}
 </h4>
 <div class="ui attached segment">
 	<div class="ui openid list">
 		<div class="item">
-			{{.i18n.Tr "settings.openid_desc"}}
+			{{.locale.Tr "settings.openid_desc"}}
 		</div>
 		{{range .OpenIDs}}
 			<div class="item">
 				<div class="right floated content">
 						<button class="ui red tiny button delete-button" data-modal-id="delete-openid" data-url="{{AppSubUrl}}/user/settings/security/openid/delete" data-id="{{.ID}}">
-							{{$.i18n.Tr "settings.delete_key"}}
+							{{$.locale.Tr "settings.delete_key"}}
 						</button>
 				</div>
 					<div class="right floated content">
@@ -20,12 +20,12 @@
 						{{if .Show}}
 							<button class="ui tiny button">
 							{{svg "octicon-eye" 16 "icon"}}
-							{{$.i18n.Tr "settings.hide_openid"}}
+							{{$.locale.Tr "settings.hide_openid"}}
 							</button>
 						{{else}}
 							<button class="ui tiny button">
 							{{svg "octicon-eye-closed" 16 "icon"}}
-							{{$.i18n.Tr "settings.show_openid"}}
+							{{$.locale.Tr "settings.show_openid"}}
 							</button>
 						{{end}}
 						</button>
@@ -42,11 +42,11 @@
 	<form class="ui form" action="{{AppSubUrl}}/user/settings/security/openid" method="post">
 		{{.CsrfTokenHtml}}
 		<div class="required field {{if .Err_OpenID}}error{{end}}">
-			<label for="openid">{{.i18n.Tr "settings.add_new_openid"}}</label>
+			<label for="openid">{{.locale.Tr "settings.add_new_openid"}}</label>
 			<input id="openid" name="openid" type="text" required>
 		</div>
 		<button class="ui green button">
-			{{.i18n.Tr "settings.add_openid"}}
+			{{.locale.Tr "settings.add_openid"}}
 		</button>
 	</form>
 </div>
@@ -54,10 +54,10 @@
 <div class="ui small basic delete modal" id="delete-openid">
 	<div class="ui icon header">
 		{{svg "octicon-trash"}}
-		{{.i18n.Tr "settings.openid_deletion"}}
+		{{.locale.Tr "settings.openid_deletion"}}
 	</div>
 	<div class="content">
-		<p>{{.i18n.Tr "settings.openid_deletion_desc"}}</p>
+		<p>{{.locale.Tr "settings.openid_deletion_desc"}}</p>
 	</div>
 	{{template "base/delete_modal_actions" .}}
 </div>