Add two more generic methods for EntityInfoWrapper

[jhrozek]

Summary

These will make it easier to construct EntityInfoWrapper messages from
the new entity handlers.

Related: #4327

Change Type

• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
• Documentation (updates or additions to documentation)
• Refactoring or test improvements (no bug fixes or new functionality)

Testing

make test + part of a larger branch

Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
• Checked that related changes are merged.

[coveralls]

coverage: 52.869% (+0.01%) from 52.857%
when pulling 18b0469 on jhrozek:ewp_generic
into 6f89a1d on stacklok:main.