Extract and refactor placeholder from navigation block edit function

[talldan]

Description

Fixes #22932

Refactors the Navigation Block's placeholder into it's own component along with all the data fetching requirements.

How has this been tested?

1. Ensure you have pages and menus created.
2. Create a navigation block in a post.
3. Try selecting the various options for creating a menu.

Screenshots

Types of changes

Code refactor (non breaking change)

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR.

[github-actions]

Size Change: -70 B (0%)

Total Size: 1.13 MB

Filename	Size	Change
build/block-editor/index.js	107 kB	+1 B
build/block-library/editor-rtl.css	7.88 kB	+1 B
build/block-library/index.js	129 kB	-84 B (0%)
build/blocks/index.js	48.1 kB	+3 B (0%)
build/components/index.js	195 kB	+2 B (0%)
build/edit-widgets/index.js	9.33 kB	-2 B (0%)
build/editor/index.js	44.8 kB	+9 B (0%)
build/format-library/index.js	7.72 kB	-1 B
build/plugins/index.js	2.56 kB	+1 B

ℹ️ View Unchanged

Filename	Size	Change
build/a11y/index.js	1.14 kB	0 B
build/annotations/index.js	3.62 kB	0 B
build/api-fetch/index.js	3.4 kB	0 B
build/autop/index.js	2.83 kB	0 B
build/blob/index.js	620 B	0 B
build/block-directory/index.js	7.22 kB	0 B
build/block-directory/style-rtl.css	892 B	0 B
build/block-directory/style.css	892 B	0 B
build/block-editor/style-rtl.css	12.1 kB	0 B
build/block-editor/style.css	12.1 kB	0 B
build/block-library/editor.css	7.89 kB	0 B
build/block-library/style-rtl.css	7.96 kB	0 B
build/block-library/style.css	7.96 kB	0 B
build/block-library/theme-rtl.css	684 B	0 B
build/block-library/theme.css	686 B	0 B
build/block-serialization-default-parser/index.js	1.88 kB	0 B
build/block-serialization-spec-parser/index.js	3.1 kB	0 B
build/components/style-rtl.css	19.5 kB	0 B
build/components/style.css	19.5 kB	0 B
build/compose/index.js	9.31 kB	0 B
build/core-data/index.js	11.4 kB	0 B
build/data-controls/index.js	1.29 kB	0 B
build/data/index.js	8.44 kB	0 B
build/date/index.js	5.47 kB	0 B
build/deprecated/index.js	772 B	0 B
build/dom-ready/index.js	568 B	0 B
build/dom/index.js	3.17 kB	0 B
build/edit-navigation/index.js	8.26 kB	0 B
build/edit-navigation/style-rtl.css	975 B	0 B
build/edit-navigation/style.css	974 B	0 B
build/edit-post/index.js	303 kB	0 B
build/edit-post/style-rtl.css	5.6 kB	0 B
build/edit-post/style.css	5.6 kB	0 B
build/edit-site/index.js	16.6 kB	0 B
build/edit-site/style-rtl.css	2.96 kB	0 B
build/edit-site/style.css	2.96 kB	0 B
build/edit-widgets/style-rtl.css	2.4 kB	0 B
build/edit-widgets/style.css	2.4 kB	0 B
build/editor/editor-styles-rtl.css	423 B	0 B
build/editor/editor-styles.css	423 B	0 B
build/editor/style-rtl.css	4.26 kB	0 B
build/editor/style.css	4.27 kB	0 B
build/element/index.js	4.64 kB	0 B
build/escape-html/index.js	733 B	0 B
build/format-library/style-rtl.css	502 B	0 B
build/format-library/style.css	502 B	0 B
build/hooks/index.js	2.13 kB	0 B
build/html-entities/index.js	622 B	0 B
build/i18n/index.js	3.56 kB	0 B
build/is-shallow-equal/index.js	710 B	0 B
build/keyboard-shortcuts/index.js	2.51 kB	0 B
build/keycodes/index.js	1.94 kB	0 B
build/list-reusable-blocks/index.js	3.12 kB	0 B
build/list-reusable-blocks/style-rtl.css	226 B	0 B
build/list-reusable-blocks/style.css	226 B	0 B
build/media-utils/index.js	5.29 kB	0 B
build/notices/index.js	1.79 kB	0 B
build/nux/index.js	3.4 kB	0 B
build/nux/style-rtl.css	616 B	0 B
build/nux/style.css	613 B	0 B
build/primitives/index.js	1.5 kB	0 B
build/priority-queue/index.js	789 B	0 B
build/redux-routine/index.js	2.85 kB	0 B
build/rich-text/index.js	14.8 kB	0 B
build/server-side-render/index.js	2.68 kB	0 B
build/shortcode/index.js	1.7 kB	0 B
build/token-list/index.js	1.28 kB	0 B
build/url/index.js	4.06 kB	0 B
build/viewport/index.js	1.85 kB	0 B
build/warning/index.js	1.14 kB	0 B
build/wordcount/index.js	1.17 kB	0 B

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[tellthemachines]

Looks good, works well!