Show non-found CS aspects in tables for deletion

[mrvisscher]

Activities and Methods that are deleted are not automatically deleted from calculations setups. With this PR we show these missing Activities and Methods in their respective CS tables so they can be deleted manually.

• closes Deleting a database does not remove activity from calculation setup #1238

Checklist

• Keep pull requests small so they can be easily reviewed.
• Update the documentation
  • For in-code documentation, please follow the numpy style guide.
  • For user documentation, please update the wiki in
    ./activity_browser/docs/wiki
• Update tests.
• Link this PR to related issues by using closing keywords.

If you have write access (otherwise a maintainer will do this for you):

• Categorize the PR by setting a good title and adding one of the labels:
  bug, feature, ui, change, documentation, breaking, ci
  as they show up in the changelog.
• Add a milestone to the PR (and related issues, if any) for the intended release.
• Request a review from another developer.

[coveralls]

coverage: 54.217% (-0.03%) from 54.245%
when pulling 5619c35 on mrvisscher:cs-act-mthd-deletion
into 0068e31 on LCA-ActivityBrowser:main.