Add formalization / clarity to current selection state

[colinmegill]

Since users can take actions given current selection (create an annotation, subset to it etc), it would be great if it were reinforced as a concept in the ui

Thanks to @happyimadesignr!

[bkmartinjr]

duplicate of #559 ?

[colinmegill]

Not quite! #559 is about a value, but we haven't implemented because it takes up too much horizontal space. I could see doing #559 in tooltip if you hover on the value - ie., if the value for tissue > heart is 10 and that is reflective of world, and you hover on 10, it would tell you: heart in current selection: 5, heart in universe: 500

This issue is really about making 'current selection' a more prominent noun in the interface, to reinforce to users that they can take an action on it (ie., subset). The mock, above, is a reminder not necessarily a spec.

Neither are urgent.

[colinmegill]

This is also an opportunity to copy current cell selection to clipboard/csv, that further reinforces that it's a list of cell ids.

[signechambers1]

Closing as a low priority for 2021