Block editing forms that are being sent (and vice versa)

[seadowg]

The user shouldn't be able to edit a finalized instance while instances are being sent. One thing we could do here is completely block the ability to edit a finalized instance, but that could be controversial.

A softer option would be to utilize the instance's changeLock during editing of a finalized instance. In that world:

• Opening a finalized instance would be blocked when the instances are locked (during auto send)
• Auto send wouldn't run when a finalized form is open

I would definitely be in favour of preventing edits if we feel we can get away with it. Interested in thoughts from @grzesiek2010 and @lognaturel on that one.