Drop schema contents when deleting

[mathemancer]

Fixes #4240

Modifies the schemas.delete RPC function to drop all objects within passed schemas, and then the schemas themselves, without CASCADE.

Technical details

• This is far safer than CASCADE, but lets users delete schemas that still contain objects
• The new version of the function accepts an array of schema OIDs to drop.
  • This allows for future UIs where we allow a user to drop a set of schemas containing interdependent objects
• The error messaging is greatly improved so that if a schema to be dropped contains dependencies of a schema which isn't to be dropped, all dependency issues will be shown.
• I updated the scenario test so that it would have failed with the previous version.

Checklist

• My pull request has a descriptive title (not a vague title like Update index.md).
• My pull request targets the develop branch of the repository
• My commit messages follow best practices.
• My code follows the established code style of the repository.
• I added tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no
  visible errors.

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[mathemancer]

@pavish I made very tiny FE changes, so I assigned you to look at those.

[pavish]

This will ignore any new files within /mathesar/static.

We have a number of icons and images here which are used in the product within /mathesar/static/non-code. We should be ignoring the exact path we need to ignore and not have a general static/ matcher here.

[pavish]

Looks great.

[mathemancer]

@pavish This should be ready for re-review.

[pavish]

LGTM!