Admin Menu filter by parent

[brianteeman]

Pull Request for Issue #38150 .

Summary of Changes

Adds a new parent filter for admin menus

Testing Instructions

Create a custom admin menu and populate with a few nested menu items for testing
Open filter options and with this PR there is a new filter that lets you filter the menu items by the parent.
Test that the filter works for both site and admin menus

This is the same as seen for site menus

[RickR2H]

I have tested this item ✅ successfully on fe68bf0

Nice feature! Works!

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[Kostelano]

I have tested this item ✅ successfully on fe68bf0

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[alikon]

RTC

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[fancyFranci]

As this is a new feature, I'll move it to 4.3. I'm sure the new release managers will be happy to have it in their release :)

[obuisard]

Great addition, thank you Brian @brianteeman