MM-55468 Ensure custom status emojis exist (#25501)

* MM-55468 Ensure custom status emojis exist

* Fix plugin API unit test

* Print underlying error as detailed error message

* Convert CustomStatusModal tests to React Testing Library and improve a11y

* Don't suggest custom statuses with non-existent emojis

* Silence test error by providing fake translation strings

server/channels/app/plugin_api_test.go

@@ -513,7 +513,7 @@ func TestPluginAPIUserCustomStatus(t *testing.T) {
 	defer th.App.PermanentDeleteUser(th.Context, user1)
 
 	custom := &model.CustomStatus{
-		Emoji: ":tada:",
+		Emoji: "tada",
 		Text:  "honk",
 	}