Revisit support for additional/unknown properties in project/service config after revert #6423
Description
This issue tracks safely reintroducing support for additional or unknown properties in project/service config files, which was originally added in PR #6196 and subsequently reverted in PR #6408 due to a regression in v1.22.4.
Context
- Issue #6407: azd panics during postprovision
- PR Adds support for additional/unknown properties on project/service config #6196 introduced broader property support for configs, but this change led to the bug described above.
- PR Revert "Adds support for additional/unknown properties on project/service config" #6408 temporarily reverts that functionality and is in v1.22.5.