Handle Commit Resubmissions

Say a user has a TODO list of "audit A and B". They opt for an incremental approach, auditing A and hitting "Commit" before working on B.

They are now in a problematic situation as the UI currently works. They need to remember to manually "clear" A before submitting B, or we when they hit "Commit" it will attempt to add *another* audit for A to the ledger.

More problematically, they may just realize "oops I forgot to add a note!" and intentionally resubmit A with the new comment.

There are many possible solutions to this, in increasing levels of difficulty:

* Fuck it get good (perhaps acceptable for the MVP)
* Encourage them to wait for the CI to do a full loop and open a new report id to work in
* Auto-clear everything (dangerous, would discard work in the case of a failure)
* Give them a clear button
* Remember what was done but somehow mark it as "done" in the UI and simply don't resubmit it (problematic if they DO want to resubmit it)
* Make our workflows understand old submissions and merge them
* Make cargo-vet itself understand "duplicate" or "overwrite" audits