Is your feature request related to a problem? Please describe.
DXC will often be unable to validate a shader targeted towards a preview shader model because there is no accompanying dxv.exe that is correctly versioned.

Describe the solution you'd like
DXC should use the internal validator by default, as described in https://github.com/microsoft/hlsl-specs/blob/main/proposals/infra/INF-0004-validator-hashing.md.

Additional context
This will prevent other repos that ingest DXC from failing tests when there are no valid DXIL.dlls that are suitable for validation for the preview shader model.