Revive --extract-shaders for dxbc bytecode extraction

[PachiMako]

teShaderCode, teShaderInstance and teShaderGroup all changed structure since at least the patch of Aug 10 '23 (Manifest 3320652641754470004).

This change reran structural analysis of teShaderCode as well as teShaderGroup which now holds a list of shaders per group. teShaderInstance is not reversed in this change since --extract-shaders does not require it to be updated (note that teShaderInstance moved from 088 to 040).

Further reversing of the fields and their associations may come in subsequent changes.

Changes:

• Improves error handling and logging for --extract-shaders
• Adds errors in codepaths that are not longer functional such as resolving file names in SaveShaderGroup and resolving previously extracted shaders using their now stale hash
• Fixup teSHADER_TYPE enum which is in fact a byte-sized bitflag with COMPUTE being inferred from no other stages being enabled
• Minimal reverse of teShaderGroup and teShaderCode headers

Verified working on overwatch build prometheus-2_23_0_0-150480 with valid dxbc for all entries of teShaderCode with the following distributions across shader types:

PIXEL (2): 112210
VERTEX (1): 21777
COMPUTE (0): 147
GEOMETRY (4): 24
VERTEX, UNKNOWN_C (129): 13
GEOMETRY, UNKNOWN_B (20): 1

[PachiMako]

Needs a few fixes before opening up for review again:

• use [StructLayout(LayoutKind.Explicit)] for the required fields
• revert the changes to teSHADER_TYPE as it was in fact still a ushort with 256 indicating COMPUTE
• fix PR to only contain the fix change