#36 group by subprojects

[wosiu]

Limit number of results - show only subprojects name instead of all available commands for all subprojects until a whole project name is already typed.

For example - assuming:

• root project has task aTaskInRoot
• 3 subprojects: :ab, :ac and :de`
• each subproject has tasks: taskA, taskB

then:

./gradlew <tab>

shows:

aTaskInRoot
ab: 
ac:
de:

./gradlew a<tab>

shows:

aTaskInRoot
ab: 
ac:

./gradlew ab:<tab>

shows:

:ab:taskA
:ab:taskB

Partially solves: https://github.com/gradle/gradle-completion/issues/36

Tested on monorepo with tens of subprojects and tasks, both bash and zsh. Without that, a developer is overwhelmed with hundreds od tasks...