Add global selection reset and add some tooltips to filter panel action icons

[JackWilb]

Does this PR close any open issues?

Closes #470

Give a longer description of what this PR addresses and why it's needed

This PR

1. Fixes an issue with resetting the currently selected visit when it's removed from the selected visits.
2. Adds a method to the store to globally reset selections
3. Adds UI for removing selections including changing how selected visit count is encoded, e.g 1_000_000 is now 1.0M
4. Add tooltips to the action icons in the filter panel

Provide pictures/videos of the behavior before and after these changes (optional)

Are there any additional TODOs before this PR is ready to go?

No

[Luke-Schreiber]

Looks good! Clearing selections makes sense here. Glad we removed the async for adding / removing selections.