option to limit the number of opened diff tools

[nitsanavni]

Sometimes, while working with approvals, one might break the code in such a way that many tests fail at once, resulting in many diff tools windows opening. Sometime all these diffs are irrelevant, because something broke.

Thoughts

• we could throttle the triggering of diff tools - allowing only a small number of windows to open at once
• we could add an action (cli?) that kills all the diff tools processes that were opened at once