R1:4041a7e0f664

Add ApplicationTransaction handling for transactions with no effect

Summary:
When a user submits an action with no effect (like an empty comment, an "abandon" on an already-accepted revision, or a "close, resolved" on a closed task) we want to alert them that their action isn't effective. These warnings fall into two general buckets:

- User is submitting two or more actions, and some aren't effective but some are. Prompt them to apply the effective actions only.
- A special case of this is where…