[xml] Missing group attributes on enum/bitfield arguments of core functions

[SunSerega]

Part of #361

1. Some glGet* functions didn't have group="GetPName".

2. glShaderBinary:
   Specification defines at least one specific value - GL_SHADER_BINARY_FORMAT_SPIR_V.
   So, i defined ShaderBinaryFormat group for it.
   
   Besides that - while looking for info i found quite a few people passing 0 as binary format. Is it some kind of special value "general format"? Should it also be added to ShaderBinaryFormat group?

3. glFenceSync and glWaitSync have flags parameter. It's reserved for now, so only 0 can be passed into them.
   I added EmptyFlags group, so that this restriction can be easier enforced in higl-level bindings.

I also applied all the same changes to extension functions, that define these functions as <alias>.

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Somewhat off topic but related questions:

• glSampleMaski takes GLbitfield argument. And, well, it is a bitfield, but it's not what GLbitfield is usually used for.
  Maybe it would make more sense to change that argument to GLuint, so it's not confused with actual enum arguments?

• I found and added few missing group="sync" attributes's in extension functions, alias to core functions that have this attribute.
  But can someone actually explain why most arguments of type GLsync also have group sync?
  Is it an old thing, from when there wasn't a GLsync type? Does it still need to exist?

[Perksey]

Thank you so much for this PR! Most of the groups look good, however...

[pdaniell-nv]

@oddhack this is approved to merge assuming you're happy with it.