Add a way to cancel Flutter commands

[pq]

If a command hangs (or appears to hang), we should have a way to cancel it:

[pq]

Update: while I think the request stands, it looks like my command hadn't hung above but was rather just very quick. When run from the commandline I see:

[~/IdeaProjects/untitled8_901210921] $ flutter packages get
Running 'flutter packages get' in untitled8_901210921... 497ms

I wonder if there shouldn't be a better indication that the command has run?

Should we print the time elapsed (as we do on the commandline)?

cc @devoncarew @danrubel

[devoncarew]

+1 to printing something in IntelliJ (flutter packages get finished. or similar).

[pq]

See also: #1923 .

[IchordeDionysos]

I had a case where I had something like this in my pubspec.yaml:

dependencies:
    flutter:
        sdk: flutter
    flutter_localizations:
        sdk: flutter
    some_pub:
        git:
           url: git@https://github.com/simpleclub/some_pub.git
           ref: master

I know there is an error git@https://github.com/simpleclub/some_pub.git should have been git@github.com:simpleclub/some_pub.git.

My point is that Flutter tried to fetch the incorrect dependency with exponential backoff and I had no way to stop the command.