Remove grid element placement props

[ruggi]

Problem:

There should be a cross button to the side of the Grid Placement inspector subsection to clear those props when set.

Fix:

Add that button, shown unless all values are defaults.

Fixes #6600

[github-actions]

Try me

[relativeci]

#14967 Bundle Size — 58.03MiB (~+0.01%).

e0c2aec(current) vs d1d46c1 master#14966(baseline)

Warning

Bundle contains 70 duplicate packages – View duplicate packages

Bundle metrics   2 changes 1 regression

	Current #14967	Baseline #14966
Initial JS	41.01MiB(~+0.01%)	41.01MiB
Initial CSS	0B	0B
Cache Invalidation	18.06%	17.95%
Chunks	20	20
Assets	22	22
Modules	4163	4163
Duplicate Modules	213	213
Duplicate Code	27.31%	27.31%
Packages	477	477
Duplicate Packages	70	70

Bundle size by type   2 changes 1 regression 1 improvement

	Current #14967	Baseline #14966
JS	58.02MiB (~+0.01%)	58.02MiB
HTML	7.37KiB (-0.25%)	7.39KiB

Bundle analysis report Branch feat/delete-grid-placement-props Project dashboard

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