Automate remove collection process

Related to #180, #181, #182, https://ucsdlibrary.atlassian.net/browse/TDX-599

What this MR suggest to do

Automate the collection deletion process:

• Add REMOVED state to flag ace collections.
• Enable node admin to turn a collection into REMOVED state, and exclude it from auditing.
• Update collection status page to display the collection state field and update the audit state for REMOVED collections.
• Extend /collections endpoint to allow retrieving collections with REMOVED state.

Screenshots

• Status page for active collection

• Remove collection form

• Finish page for removing collection

• Status page for REMOVED collection