[MM-37772] Idiomatic naming (URL, URI, API) (#18128)

* s/Url/URL/g & s/Uri/URI/g

* s/Api/API/g

api4/post_local.go

@@ -4,7 +4,7 @@
 package api4
 
 func (api *API) InitPostLocal() {
-	api.BaseRoutes.Post.Handle("", api.ApiLocal(getPost)).Methods("GET")
+	api.BaseRoutes.Post.Handle("", api.APILocal(getPost)).Methods("GET")
 
-	api.BaseRoutes.PostsForChannel.Handle("", api.ApiLocal(getPostsForChannel)).Methods("GET")
+	api.BaseRoutes.PostsForChannel.Handle("", api.APILocal(getPostsForChannel)).Methods("GET")
 }