Adding keyboard enter and spacebar functionality for the Tree component

[priyankar205]

1. Added open & close subtree functionality (for accessibility) from keyboard.

[codecov]

Codecov Report

Merging #1233 into master will decrease coverage by 0.02%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master    #1233      +/-   ##
==========================================
- Coverage   83.21%   83.19%   -0.03%     
==========================================
  Files         754      754              
  Lines        8913     8918       +5     
  Branches     1194     1194              
==========================================
+ Hits         7417     7419       +2     
- Misses       1482     1485       +3     
  Partials       14       14

Impacted Files	Coverage Δ
packages/react/src/components/Tree/TreeItem.tsx	62.5% <ø> (+1.89%)	⬆️
packages/react/src/components/Tree/TreeTitle.tsx	60.86% <0%> (-12.82%)	⬇️
.../accessibility/Behaviors/Tree/treeTitleBehavior.ts	100% <100%> (ø)	⬆️

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[codecov]

Codecov Report

Merging #1233 into master will decrease coverage by 0.01%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master    #1233      +/-   ##
==========================================
- Coverage   83.21%   83.19%   -0.02%     
==========================================
  Files         754      754              
  Lines        8912     8916       +4     
  Branches     1262     1194      -68     
==========================================
+ Hits         7416     7418       +2     
- Misses       1482     1484       +2     
  Partials       14       14

Impacted Files	Coverage Δ
packages/react/src/components/Tree/TreeTitle.tsx	66.66% <0%> (-7.02%)	⬇️
.../accessibility/Behaviors/Tree/treeTitleBehavior.ts	100% <100%> (ø)	⬆️

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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