Support for user-created groups of apps

[ninavizz]

This is a child issue within the epic #6665

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The problem you're addressing (if any)
Users from #6573 overwhelmingly supported and asked for the ideas of user-created groups for both VMs and Apps.
This Issue is to focus on the development of that capability on the backend and in the GUI—but just for apps, not VMs.

Describe the solution you'd like
The Jackie prototype suggests what an already created group of apps might look like in the App Menu (in the sub-menu for McKinsey). The interaction and visual design for how users might create those groups, feels like the strongest outstanding challenge. I've looked into doing this, lightly, in the Applications tab in each qube's Settings panel. Not sure if that's the right place, though.

Where is the value to a user, and who might that user be?
Can pull quotes into here from survey. TL;DR "Make sense of the chaos of too many VMs, rather than just have fewer VMs"

Describe alternatives you've considered
Looong, scrolling lists. :)

Additional context
Far-in-future enhancement to #5677