Introduce an organizational "endorsement" stamp

[acoffman]

This will be leveraged for SC-VCEP approval status as well as potentially FDA recognition status.

• [x] Introduce a status field to Organizations indicating if they are allowed to endorse assertions or not (do we need separate status specifically for approved vceps or is just a general "can endorse things" status fine?)
• [x] Add a field on the organization membership table indicating if a user can approve on behalf of that organization
• [x] Add admin page support for managing the above (with hopes to integrate more directly with the clingen system in the future)
• [x] Add a table for organizational endorsements (org id, approving user id, timestamps, status)
• [x] When viewing an approved assertion, if a user is a member of an org with endorsement powers AND that user can endorse on behalf of the org, show an "endorse this on behalf of org" button
• [x] When clicked we should display a confirmation modal indicating that this represents a formal organizational endorsement and prominently displaying the org that will be used.
• [x] Allow filtering Assertions by organizational endorsements in the API (and browse table view?)
• [x] On org pages, display all endorsed assertions
• [x] On assertion pages display all current endorsements
• [x] If data underlying an assertion changes (variants, eids, etc) do not revoke the endorsement but mark that it may require review with an explanation of what changed (do we need to make endorsements commentable or something for this? perhaps we need history of who reevaluated it? if so, maybe we should re-use our flagging mechanism for this but not display it as a flag on the assertion?)
• [x] Display logs on assertion pages for endorsements
• [x] UI for formally revoking an endorsement (maybe similar to the revert button?)
• [x] allow comment (activity note) on revocation

Need decisions:

• Do we want a Badge on assertion tags for endorsed assertions
• Should "requires_review" be displayed the same as "active" (e.g. include in endorsed assertion tab, assertion ribbon, assertion summary, etc)
• What activities would trigger an endorsement to change status to "requires_review"