WS-2375: Add observing types to wrester and metadata for standard cal and imaging.

The story description asks for the abstract to be added as well, however it was not included here after discussion with Mark.

There are unit tests for the changed code in both test_aat_wrest and test_metadata_wrester; while I updated the preexisting tests in test_aat_wrest, the tests in test_metadata_wrester should be considered the canonical unit tests for this code. Further, one test in test_aat_wrest is failing as of this MR; this is unrelated to the code changes here and there's a tech debt ticket to address it.