Navigation: Preload Navigation screen API requests

[noisysocks]

Closes #24642.

Use wp.apiFetch.createPreloadingMiddleware to preload the initial API requests made by the Navigation screen. This makes the screen appear quicker.

To test

1. Open DevTools and go to the Network tab. Filter it so that only XHR requests appear.
2. Go to Gutenberg → Navigation (beta).
3. No XHR requests should have been made.

[github-actions]

Size Change: 0 B

Total Size: 1.16 MB

ℹ️ View Unchanged

Filename	Size	Change
build/a11y/index.js	1.14 kB	0 B
build/annotations/index.js	3.67 kB	0 B
build/api-fetch/index.js	3.44 kB	0 B
build/autop/index.js	2.82 kB	0 B
build/blob/index.js	620 B	0 B
build/block-directory/index.js	7.96 kB	0 B
build/block-directory/style-rtl.css	953 B	0 B
build/block-directory/style.css	952 B	0 B
build/block-editor/index.js	126 kB	0 B
build/block-editor/style-rtl.css	10.7 kB	0 B
build/block-editor/style.css	10.7 kB	0 B
build/block-library/editor-rtl.css	8.36 kB	0 B
build/block-library/editor.css	8.36 kB	0 B
build/block-library/index.js	133 kB	0 B
build/block-library/style-rtl.css	7.42 kB	0 B
build/block-library/style.css	7.43 kB	0 B
build/block-library/theme-rtl.css	729 B	0 B
build/block-library/theme.css	730 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/blocks/index.js	47.6 kB	0 B
build/components/index.js	200 kB	0 B
build/components/style-rtl.css	15.7 kB	0 B
build/components/style.css	15.7 kB	0 B
build/compose/index.js	9.68 kB	0 B
build/core-data/index.js	11.8 kB	0 B
build/data-controls/index.js	1.29 kB	0 B
build/data/index.js	8.55 kB	0 B
build/date/index.js	5.38 kB	0 B
build/deprecated/index.js	772 B	0 B
build/dom-ready/index.js	568 B	0 B
build/dom/index.js	4.47 kB	0 B
build/edit-navigation/index.js	11 kB	0 B
build/edit-navigation/style-rtl.css	1.12 kB	0 B
build/edit-navigation/style.css	1.12 kB	0 B
build/edit-post/index.js	304 kB	0 B
build/edit-post/style-rtl.css	5.61 kB	0 B
build/edit-post/style.css	5.61 kB	0 B
build/edit-site/index.js	17 kB	0 B
build/edit-site/style-rtl.css	3.06 kB	0 B
build/edit-site/style.css	3.06 kB	0 B
build/edit-widgets/index.js	11.8 kB	0 B
build/edit-widgets/style-rtl.css	2.45 kB	0 B
build/edit-widgets/style.css	2.45 kB	0 B
build/editor/editor-styles-rtl.css	537 B	0 B
build/editor/editor-styles.css	539 B	0 B
build/editor/index.js	45.3 kB	0 B
build/editor/style-rtl.css	3.8 kB	0 B
build/editor/style.css	3.79 kB	0 B
build/element/index.js	4.65 kB	0 B
build/escape-html/index.js	733 B	0 B
build/format-library/index.js	7.71 kB	0 B
build/format-library/style-rtl.css	547 B	0 B
build/format-library/style.css	548 B	0 B
build/hooks/index.js	2.13 kB	0 B
build/html-entities/index.js	621 B	0 B
build/i18n/index.js	3.56 kB	0 B
build/is-shallow-equal/index.js	711 B	0 B
build/keyboard-shortcuts/index.js	2.52 kB	0 B
build/keycodes/index.js	1.94 kB	0 B
build/list-reusable-blocks/index.js	3.11 kB	0 B
build/list-reusable-blocks/style-rtl.css	476 B	0 B
build/list-reusable-blocks/style.css	476 B	0 B
build/media-utils/index.js	5.33 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	671 B	0 B
build/nux/style.css	668 B	0 B
build/plugins/index.js	2.56 kB	0 B
build/primitives/index.js	1.41 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	13.9 kB	0 B
build/server-side-render/index.js	2.77 kB	0 B
build/shortcode/index.js	1.7 kB	0 B
build/token-list/index.js	1.27 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

_{compressed-size-action}

[talldan]

There seems to be a couple of (possibly caching?) bugs in this branch that I couldn't reproduce on master.

• When deleting the last/only menu, the screen briefly changes, but then the deleted menu re-appears.
• When no menus are present (delete your last menu and then reload the page) and creating a menu for the first time, the 'Create Menu' UI is still shown after the menu has been created.

[spacedmonkey]

LGTM

[noisysocks]

There seems to be a couple of (possibly caching?) bugs in this branch that I couldn't reproduce on master.

• When deleting the last/only menu, the screen briefly changes, but then the deleted menu re-appears.
• When no menus are present (delete your last menu and then reload the page) and creating a menu for the first time, the 'Create Menu' UI is still shown after the menu has been created.

Hm, bugger. I suspect the way we handle preloading in Gutenberg is flawed. We're caching requests at the @wordpress/api-fetch level which assumes that endpoints will always return the same data during the application's lifespan. This isn't true when we're hitting collection endpoints for entities that can be created and deleted, though.

Probably we'll have to look at implementing preloading at the @wordpress/data level. Something similar to Redux where you bootstrap the data store with some initial data.

Closing for now.