Block Editor: Simplify InspectorControlsFill rendering logic

[Mamaduka]

What?

I was experimenting with deferred inspector rendering and realized the component exit points became a bit hard to follow. This is my attempt to simplify it a little bit.

Changes

• Names the three context reads as locals (isSelectedBlock, isPatternEditing, isInListViewTree) instead of repeating symbol lookups.
• Merges the two visibility checks into one if/else if. The second check's condition was exactly the else branch of the first.
• Splits the List View popover case into a rendersInListView flag plus its own guard, so routing (which fill to use) is separate from gating (is this the selected block).
• Returns once, with a single StyleProvider wrapping either fill.
• Passes children as JSX children rather than as a prop.

Testing Instructions

I think this should have decent e2e test coverage, but a smoke test controls for various blocks - Navigation, Template Parts, Text blocks. Confirm they are rendered as before.

Testing Instructions for Keyboard

Same.

Use of AI Tools

Assisted by Claude.

[github-actions]

Size Change: -6 B (0%)

Total Size: 7.81 MB

📦 View Changed

Filename	Size	Change
build/scripts/block-editor/index.min.js	434 kB	-6 B (0%)

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[im3dabasia]

Thanks for working on the issue!

LGTM ✅

[github-actions]

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Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
Co-authored-by: im3dabasia <im3dabasia1@git.wordpress.org>

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