Fix bug with storing element declaration references

[justinfagnani]

The FirestoreRepository was calculating the reference string for the element declaration incorrectly when the definition/export (the define() call) was in a different module from the declaration (the class). It was assuming that the modules were the same, so the element page couldn't then find the declaration in the manifest when it was showing element details.

This adds a few tests that were passing before the fix as I investigated the issue, and one catalog test that fails without the fix.