Matthew Pickering authored Dec 24, 2022 and Marge Bot committed Jan 24, 2023

The key part of this change is to store a UnitId in the
`UsageHomeModule` and `UsageHomeModuleInterface`.

* Fine-grained dependency tracking is used if the dependency comes from
  any home unit.
* We actually look up the right module when checking whether we need to
  recompile in the `UsageHomeModuleInterface` case.

These scenarios are both checked by the new tests (
multipleHomeUnits_recomp and multipleHomeUnits_recomp_th )

Fixes #22675