Address PR feedback

- Delete derived struct ShaderEntryMDInfo and move the functionlaity
  in its methods as static functions.
- Add class DiagnosticInfoModuleFormat derived from DiagnosticInfo for
  diagnostics reporting in TranslateMetadata pass
- Consume Resource metadata information constructed by emitResourceMetadata()
- Move generation of metadata for validator version, Shader Model
  version, DXIL Version into separate functions.
- Changes to accept input shader modules with no entry functions
- Update/emit named metadata dx.valver only if Metadata Analysis info
  contains the information; it is not created to with a default value,
  if it is not.

Author: bharadwajy