Default subproject for implicit completion

[paour]

The GRADLE_COMPLETION_UNQUALIFIED_TASKS option causes the completion script to go over all subprojects, potentially pulling in too many tasks. Android apps generally always use :app: for the main subproject, could another env var direct the script to autocomplete for that by default?

[eriwen]

Yes, I'd be very happy to consider a PR here especially that makes completion better for Android projects. Is that something you'd be willing to submit?

[paour]

With my bash skills, you'd have to rewrite whatever I contributed ;-).

What I had in mind was not necessarily Android-specific: the variable could be set to whatever the "usual" default subproject the developer uses.

[eriwen]

Okay, thanks for the clarification. That is helpful.

[mwos-sl]

I think that could be easily handled by: #88
I've already implemented such task. It can be easily extended. I can share the code.
To apply it, this PR needs to be accepted: #89