Add an ability to automatically rerun test/main class on code changes

[tgodzik]

Is your feature request related to a problem? Please describe.
This would work very similar to sbt sbt ~run

Describe the solution you'd like
We could add a flag to debug command so that Metals reruns after recompilation was done.

This will need some work on a frontend to make sure it works sensibly.

Describe alternatives you've considered
Running via sbt sbt ~run

Additional context
This could work also with for example Play Framework. After changes that add an option to autoresolve target ID, this should be perfectly doable.

Search terms:
watch hot code reload

[A-UNDERSCORE-D]

Would love some hot code reloading. would make some bits of dev a breeze