Is your feature request related to a problem? Please describe.
I ran Dart: Apply Fix All in Workspace with a list of 4887 diagnostic to fix, and although it ran fine, I could not tell that it was running.

Describe the solution you'd like
I'd like to see a toast to indicate that some processing is happening.

Describe alternatives you've considered
Doing it from the terminal allows me to see that the process is running since I can't write more things.