fix: Problems with multiplayer-netfox example

[zibetnu]

I ran into three issues when taking a look at the netfox example.

First, the connect_ui issue mentioned in #134 showed up here as well. I applied the same fix.

Second, I noticed that the player's _tick function wasn't getting called. It looks like it should be connected to NetworkTime's on_tick signal, so I went ahead and did that as a fix.

Third, I can't get the players to move and haven't figured out why. The input works and velocity is set, but nothing noticeable happens when move_and_slide is called. Hopefully you'll know what needs to be done to fix this, and then the fix can be part of this or a different pull request.

Oh also, Godot automatically removed a line from player.tscn and I thought it was relevant enough to be part of this pull request.

[elementbound]

Thanks for the PR @zibetnu! I've suggested some changes, which I'm happy to implement myself. Let me know if you'd like to tackle the updates :)
If not, I can either open a new PR based on your changes, or update your fork if you give me write permission.

[zibetnu]

Done! I decided to make those changes myself because I'm trying to familiarize myself with netfox anyway.

I also invited you to have write access. Please let me know if there was a better way to do that.