Replace lib-ui useSelectionState with a batteries implementation, fix related quirks, handle shift+click multiselect and bulk selection

[mturley]

Addresses some tech debt that has been bugging me for a while. The selection feature is now fully integrated alongside the other features and no longer depends on the migtools lib-ui useSelectionState (which will be retired). The selection feature handles the behavior it used to plus non-selectable items, shift+click to select multiple items, and logic related to bulk select (specifically around the differences between client and server tables -- we can't "select all" on a server-driven table because we don't know all the item ids).

Also implements the Selection feature example in docs in order to test drive these changes.

One thing to note here is that I've also renamed all of the get*DerivedState functions to use*DerivedState since we needed to call a useMemo in useSelectionDerivedState which means it needed hook naming. The other derived state hooks aren't calling any hooks currently, but consistent naming made sense to me and now we can introduce future memoization or whatever other hook usage in them as necessary without renaming stuff.