[post-mvp] Figure out how to re-file/re-sign a Filing after it's already been signed

[jcadam14]

How do we know when a filing needs to be re-signed once changes have been made to an already-signed filing?

Suggestions from Hans:

• Associate signatures to submissions rather than filings. Then on the signing screen if the submission associated to the filing isn't signed, you now you need to sign it? That wouldn't fix needing to re-sign after changing contact info or institution data, though.

• Disassociate a signature from a filing if anything changes on a signed filing. Not sure how that'd work in the current one-to-many sigs per filing. Add a invalid/expired type flag?

• Alternatively, don't have it as a one-to-many, and just hang the signature off the filing record similar to other fields. If anything changes on the filing, the signature gets dropped. We lose history of signature, but makes it simple. If we want history, we could implement it the same way we do for institution data at a later time.

Jason's suggestion:

• Keeps signatures as is, but if anything else changes (like a new submission, contact info, institution snapshot id), drop the confirmation_id. That way we keep the history of signatures, but the confirmation_id is the thing showing if the current Filing has been signed. When it is re-signed, create a new signature and confirmation id.