Fix client lua error/reduce network usage a bit

[Astralcircle]

Fixes:

[[ACF-3] Armored Combat Framework] lua/acf/core/networking/networking_cl.lua:57: bad argument #1 to 'ToTable' (string expected, got nil)
1. ToTable - [C]:-1
 2. func - lua/acf/core/networking/networking_cl.lua:57
  3. unknown - lua/includes/extensions/net.lua:38

We can avoid writing UInt on the server side as we can use the message length instead. I didn't do it on the client as I don't know if it can cause problems with spam messages.

[Astralcircle]

Need to test for stability