Increment/Decrement Fractional Grid Tracks

[seanparsons]

Problem:
It would be helpful if fractional grid track values can be incremented or decremented using the arrow keys.

Fix:
Modified the keyboard event handler for the columns and rows to increment and decrement just the fractional values.

Commit Details:

• Added isFR utility function.
• Modified GridExpressionInput.onKeyDown to handle arrow up and down but only for fractional values.

Manual Tests:
I hereby swear that:

• I opened a hydrogen project and it loaded
• I could navigate to various routes in Play mode

[github-actions]

Try me

[relativeci]

#14924 Bundle Size — 57.98MiB (~+0.01%).

e567e80(current) vs 916e8b9 master#14921(baseline)

Warning

Bundle contains 70 duplicate packages – View duplicate packages

Bundle metrics   2 changes 1 regression

	Current #14924	Baseline #14921
Initial JS	40.96MiB(~+0.01%)	40.96MiB
Initial CSS	0B	0B
Cache Invalidation	17.99%	17.91%
Chunks	20	20
Assets	22	22
Modules	4152	4152
Duplicate Modules	213	213
Duplicate Code	27.33%	27.33%
Packages	477	477
Duplicate Packages	70	70

Bundle size by type   2 changes 1 regression 1 improvement

	Current #14924	Baseline #14921
JS	57.97MiB (~+0.01%)	57.97MiB
HTML	7.37KiB (-0.25%)	7.39KiB

Bundle analysis report Branch feature/increment-decrement-grid... Project dashboard

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