feat(mfe): support MFE config v2 (#9471)
### Description
Add support for MFE v2 configuration to `turbo` along with supporting
multiple default configuration file names.
A few highlights of this PR:
- Generalize MFE config interface to support multiple schemas
- Add support for MFE v2 schema
- Refactor MFE configuration loading by `turbo` so it can be unit tested
- Rename of any casing permutation to `Microfrontends`
Reviewing each commit individually should be helpful as I did code moves
to ensure that we follow `Microfrontends` as the casing scheme
throughout the code.
### Testing Instructions
Added unit tests for configuration loading.
Manual test in a MFE v2 enabled monorepo.
