chore(config): add undocummented `remote` types to `turbo.json` schema (#9073)
### Description
There has been an undocumented `remoteCache` field in `turbo.json` for
quite awhile (at least since 1.10). This PR adds documentation for the
it.
### Testing Instructions
Added unit tests to verify that when these are set in `turbo.json` they
are respected in the built config.