Generalized vtables

[codemob-dev]

Fixes #2211

This is a prototype, I would like feedback on if this is the right direction to go in or not.

[codemob-dev]

I made the hashmap comptime which simplifies the interface a bit.

[Argmaster]

When you're on it, could you implement inheritance too?

[Argmaster]

jk

[codemob-dev]

When you're on it, could you implement inheritance too?

Technically this is one-level inheritance

[codemob-dev]

How bad are the error messages (e.g. on missing or incorrect functions)?

When removing the onLoadClient function from the chest I get this error:

src/utils/meta.zig:28:8: error: VTable missing field 'onLoadClient'
       @compileError("VTable missing field '" ++ field.name ++ "'");
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/utils/meta.zig:8:53: note: called at comptime here
  const map: std.StaticStringMap(VTable) = createMap();