fix: Grid making unnecessary onSelectionChanged calls

[mattrunyon]

Needed as part of DH-19292 to ensure we don't emit duplicate selection events. Even with debouncing, we might emit the event, and then emit the same selection (in a different array reference) on mouse up. This fixes that so we don't emit the unnecessary events if the mouse up did not remove selections

There are still some quirks around the selection events like when using ctrl+click+drag to deselect part of a range, onSelectionChanged is emitted with the subtracted portion as an extra range (e.g., [[0, 5], [1, 2]]) until mouse up which commits the selection and removes the overlapping ranges ([[0, 0], [3, 5]]). On the dh.ui side I'm just consolidating the ranges, but would probably be good to fix that at some point.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 44.58%. Comparing base (1c9a8ed) to head (842692d).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2471      +/-   ##
==========================================
- Coverage   47.27%   44.58%   -2.69%     
==========================================
  Files         727      757      +30     
  Lines       39767    42397    +2630     
  Branches     9949    10847     +898     
==========================================
+ Hits        18800    18903     +103     
- Misses      20956    23483    +2527     
  Partials       11       11              

Flag	Coverage Δ
unit	44.58% <100.00%> (-2.69%)	⬇️

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[bmingles]

LGTM