Never use /api/v1 from Gitea UI Pages (#19318)

Reusing `/api/v1` from Gitea UI Pages have pros and cons.
Pros:
1) Less code copy

Cons:
1) API/v1 have to support shared session with page requests.
2) You need to consider for each other when you want to change something about api/v1 or page.

This PR moves all dependencies to API/v1 from UI Pages.

Partially replace #16052

routers/api/v1/notify/notifications.go

@@ -26,7 +26,7 @@ func NewAvailable(ctx *context.APIContext) {
 }
 
 func getFindNotificationOptions(ctx *context.APIContext) *models.FindNotificationOptions {
-	before, since, err := utils.GetQueryBeforeSince(ctx)
+	before, since, err := context.GetQueryBeforeSince(ctx.Context)
 	if err != nil {
 		ctx.Error(http.StatusUnprocessableEntity, "GetQueryBeforeSince", err)
 		return nil