Cloud scrolling for 2D tags selector

For cloud selector (see ARK-Builders/ark-components-android#7) in _2D_ mode, we can do tricky scrolling to fit only part of the cloud on the screen.

Let's say that we use _distance from center_ to represent some metric (freshness or coupling from ARK-Builders/ark-components-android#13 ). When we have too much of tags, it is difficult to fit them all on the screen, so we would show the most central tags and place the rest beyond the screen. Now, imagine that we want to show the border of the cloud. We can just zoom-out everything in the middle of it, releasing screen space for the cloud border.

The middle of tags cloud can be shown by zooming-out everything what is closer to the center, and putting everything what is further from the center beyond the screen. Let's present a user with a slider allowing her to choose how much tags to zoom-out and by moving the slider it becomes possible to overview the whole cloud.

No files, tests, or entry points are named. Start by reading the referenced cloud-selector issue ARK-Builders/ark-components-android#7 and metric issue #13, then locate the existing 2D selector; done means the slider can reveal the full tag cloud while preserving the described distance-from-center behavior.

Written by the indexing model from the issue text.