Grid advanced modal color/stretch tweaks

[ruggi]

Problem:

1. The advanced grid modal always shows selected dropdown value with a subdued color
2. The advaned grid modal doesn't offer stretch as an option for justify/align.

Fix:

1. Fix the entries which are incorrectly set with placeholder: true
2. Use FlexAlignment for the options of the align section
3. Add stretch to the FlexJustifyContent enum

Fixes #6558

[github-actions]

Try me

[relativeci]

#14853 Bundle Size — 57.98MiB (~+0.01%).

82c9423(current) vs 916e8b9 master#14846(baseline)

Warning

Bundle contains 70 duplicate packages – View duplicate packages

Bundle metrics   2 changes 1 regression

	Current #14853	Baseline #14846
Initial JS	40.96MiB(~+0.01%)	40.96MiB
Initial CSS	0B	0B
Cache Invalidation	18.04%	17.88%
Chunks	20	20
Assets	22	22
Modules	4153	4153
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 #14853	Baseline #14846
JS	57.97MiB (~+0.01%)	57.97MiB
HTML	7.37KiB (-0.25%)	7.39KiB

Bundle analysis report Branch fix/grid-advanced-modal-tweak Project dashboard

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