Create Metadata UI for Admins to update metafrom linked to items

Context

The HHMI team are working off an out-of-date metadata spreadsheet to communicate content updates (as comments in the sheet). This process is prone to human error and very time-consuming. (See #401 as an example).

Proposal

Allow admins to edit metadata in the the AB.

Move metadata to the database and expose for editing through a form in the Admin area. Admins should be able to add, edit and delete metadata values for all the existing metadata fields.

Implementation (if applicable)

Alternative approaches (if applicable)

1. Write script to convert metadataValues.js file to excel for easy editing by HHMI team
2. Write script to convert the updated excel file to metadataValues.js file

Scheduling