[MM-18331] When patching a bot send websocket notification (#12373)

* When patching a bot, perform these two additional steps:

1. Update the user.UpdateAt value for the user/bot.

2. send the websocket event so all clients know a user update has
occured. This will tell clients to update the displayname

* Add check for UpdateAt.  Check that createdBot.UpdateAt is not equal
to patchedBot.UpdateAt

* re-add unintentional empty line delete in previous commit

* Don't create a fake updateAt time.  Let the Update() method handle the
change. User the returned updateUser for sending updated user event

app/bot_test.go

@@ -172,6 +172,9 @@ func TestPatchBot(t *testing.T) {
 		patchedBot, err := th.App.PatchBot(createdBot.UserId, botPatch)
 		require.Nil(t, err)
 
+		// patchedBot should create a new .UpdateAt time
+		require.NotEqual(t, createdBot.UpdateAt, patchedBot.UpdateAt)
+
 		createdBot.Username = "username2"
 		createdBot.DisplayName = "updated bot"
 		createdBot.Description = "an updated bot"