[Feature Request] Integrate container hash functionality into internal validator

[python3kgae]

Is your feature request related to a problem? Please describe.
With validation hash open sourced at 84f68ed.
The internal validator could have the ability to do the validation hash work.
This will help cases where the compiling and hashing need to be in separate step when dxil.dll cannot find.

Describe the solution you'd like
Internal validator and external validator will share the same code which do the validation hash.

Describe alternatives you've considered
Remove dxil.dll and perform only the validation hash in dxc.
This change will cause use cases that require only dxil.dll to stop working.

Additional context
dxil.dll will be part of dxc repo (#6808)