Upgrade D3D12 Agility SDK to 1.619.5

[Marijn Suijten (MarijnS95)]

A few smaller fixes with resulting API changes, following https://devblogs.microsoft.com/directx/directx12agility/:

Fixes in .4:

• Tight alignment (USE_TIGHT_ALIGNMENT) fixes:
  • Lift the Alignment==0 requirement; callers can now specify a minimum alignment within [specMin, specMax].
  • Extend the tight-alignment floor to textures.
• Revised View Creation fixes:
  • Fixed the runtime rejecting implicit size (size = 0) when creating SRVs and UAVs
  • Fixed CreateUnorderedAccessView returning CREATE_UNORDEREDACCESS_VIEW_INVALID_COUNTER_USAGE for byte-offset UAVs with valid, 4096-aligned BufferByteOffset.CounterOffsetInBytes