feat: Expandable rows shows tooltip

[emilyhuxng]

Closes #1061

Upon hovering an expandable row, display a tooltip with instructions on how to expand or expand all children. The tooltip closes on any action but shows again if you move on the expandable row.

[codecov]

Codecov Report

Merging #1068 (6475109) into main (69266f2) will decrease coverage by 0.09%.
The diff coverage is 7.69%.

@@            Coverage Diff             @@
##             main    #1068      +/-   ##
==========================================
- Coverage   41.94%   41.86%   -0.09%     
==========================================
  Files         431      432       +1     
  Lines       32477    32555      +78     
  Branches     8176     8191      +15     
==========================================
+ Hits        13622    13628       +6     
- Misses      18802    18874      +72     
  Partials       53       53              

Flag	Coverage Δ
unit	41.86% <7.69%> (-0.09%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...d/src/mousehandlers/IrisGridRowTreeMouseHandler.ts	5.66% <5.66%> (ø)
packages/iris-grid/src/IrisGridRenderer.ts	24.36% <7.14%> (-0.49%)	⬇️
packages/iris-grid/src/IrisGrid.tsx	27.36% <18.18%> (-0.07%)	⬇️

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