Fix improved gradle hotswap detection

[gaiazov]

@vladsoroka I tested improved gradle hotswap detection in EAP build of 2021.2 and realized that there was a bug in the implementation.

The implementation was marking too many directories as dirty roots. Marking all folders as dirty roots resulted in all class files being hot swapped in our test project - the implementation was not working as intended.

The fix is to only mark directories as dirty roots for outputs that don't have a path - i.e. when Gradle task declares output as a file and not as a folder, such as the jar task.

Original implementation of improved Gradle hotswap detection is in #1551

[gaiazov]

@vladsoroka I'm really hoping for this to make it into 2021.2 release, any chance this PR can be merged?

[gaiazov]

bump @vladsoroka still waiting for review

[gaiazov]

Still waiting. Is there anything I can do to help?

[nskvortsov]

I apologize for the delay. Will run this through our CI and merge, if successful.