refactor(turborepo): derive `Opts` from `Config` (#8759)
### Description
Changed `Opts` to be derived from more than just `RunArgs` and
`ExecutionArgs`. This means that `Opts` contains the fully resolved
config, which gets rid of some messy mutable logic in `RunBuilder` and
creates a single source of truth.
### Testing Instructions
Existing tests cover this pretty well.
