chore: Implement MfeConfigProvider and TaskAccessProvider traits (#11359)
## Summary
Implement the abstraction traits from `turborepo-task-executor` for the
concrete types in `turborepo-lib`:
- **`MicrofrontendsConfigs`** now implements `MfeConfigProvider`
- **`TaskAccess`** now implements `TaskAccessProvider`
## Testing
- `cargo test -p turborepo-task-executor` - 7 tests pass
- `cargo test -p turborepo-lib --lib` - 253 tests pass