[pgstac] Delete items using collection id

[gadomski]

Related Issue(s):

• Closes Unable to delete item if it is present with same id in the multiple collections #456
• Closes in pgstac transaction extension delete operation, any item with the given id may be deleted #381

Description:

Uses both collection_id and item_id to delete items. Includes a new context manager, translate_pgstac_errors, which converts pgstac exceptions to their FastAPI form. Previously this was internal to dbfunc.

PR Checklist:

• Code is formatted and linted (run pre-commit run --all-files)
• Tests pass (run make test)
• Documentation has been updated to reflect changes, if applicable, and docs build successfully (run make docs)
• Changes are added to the CHANGELOG.