Nav Block: Avoid hiding submenu when adding a link

[talldan]

Description

Related #20852, #21033

Nav Block submenus are only visible when hover or focus is within the submenu. This causes an issue in the editor where a Navigation Link in a nested submenu can be selected, but because focus is in a Toolbar or LinkControl (which are popovers), the submenu hides, and the user can no longer see what they're editing.

This PR adds editor only styles to solve that issue—when any Navigation Link block in a submenu is selected the list now receives the .is-parent-of-selected-block class name which is used to ensure the submenu stays visible.

How has this been tested?

Manual Testing

1. Add a navigation block
2. Attempt to add navigation link in a submenu
3. Observe the submenu now stays visible when focus is in the link control.

Screenshots

Before

After

Types of changes

Bug fix (non-breaking change which fixes an issue)

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: +80 B (0%)

Total Size: 856 kB

Filename	Size	Change
build/block-library/editor-rtl.css	7.24 kB	+29 B (0%)
build/block-library/editor.css	7.24 kB	+30 B (0%)
build/block-library/index.js	110 kB	+21 B (0%)

ℹ️ View Unchanged

Filename	Size	Change
build/a11y/index.js	998 B	0 B
build/annotations/index.js	3.43 kB	0 B
build/api-fetch/index.js	3.39 kB	0 B
build/autop/index.js	2.58 kB	0 B
build/blob/index.js	620 B	0 B
build/block-directory/index.js	6.02 kB	0 B
build/block-directory/style-rtl.css	760 B	0 B
build/block-directory/style.css	760 B	0 B
build/block-editor/index.js	100 kB	0 B
build/block-editor/style-rtl.css	10.9 kB	0 B
build/block-editor/style.css	10.9 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	669 B	0 B
build/block-library/theme.css	671 B	0 B
build/block-serialization-default-parser/index.js	1.65 kB	0 B
build/block-serialization-spec-parser/index.js	3.1 kB	0 B
build/blocks/index.js	57.5 kB	0 B
build/components/index.js	191 kB	0 B
build/components/style-rtl.css	15.8 kB	0 B
build/components/style.css	15.7 kB	0 B
build/compose/index.js	6.21 kB	0 B
build/core-data/index.js	10.6 kB	0 B
build/data-controls/index.js	1.04 kB	0 B
build/data/index.js	8.2 kB	0 B
build/date/index.js	5.37 kB	0 B
build/deprecated/index.js	771 B	0 B
build/dom-ready/index.js	568 B	0 B
build/dom/index.js	3.06 kB	0 B
build/edit-post/index.js	91.2 kB	0 B
build/edit-post/style-rtl.css	8.47 kB	0 B
build/edit-post/style.css	8.46 kB	0 B
build/edit-site/index.js	5.56 kB	0 B
build/edit-site/style-rtl.css	2.62 kB	0 B
build/edit-site/style.css	2.62 kB	0 B
build/edit-widgets/index.js	4.43 kB	0 B
build/edit-widgets/style-rtl.css	2.58 kB	0 B
build/edit-widgets/style.css	2.58 kB	0 B
build/editor/editor-styles-rtl.css	381 B	0 B
build/editor/editor-styles.css	382 B	0 B
build/editor/index.js	43.8 kB	0 B
build/editor/style-rtl.css	3.97 kB	0 B
build/editor/style.css	3.96 kB	0 B
build/element/index.js	4.44 kB	0 B
build/escape-html/index.js	733 B	0 B
build/format-library/index.js	6.95 kB	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	1.93 kB	0 B
build/html-entities/index.js	621 B	0 B
build/i18n/index.js	3.49 kB	0 B
build/is-shallow-equal/index.js	711 B	0 B
build/keyboard-shortcuts/index.js	2.3 kB	0 B
build/keycodes/index.js	1.69 kB	0 B
build/list-reusable-blocks/index.js	2.99 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	4.83 kB	0 B
build/notices/index.js	1.58 kB	0 B
build/nux/index.js	3.01 kB	0 B
build/nux/style-rtl.css	616 B	0 B
build/nux/style.css	613 B	0 B
build/plugins/index.js	2.54 kB	0 B
build/primitives/index.js	1.5 kB	0 B
build/priority-queue/index.js	780 B	0 B
build/redux-routine/index.js	2.83 kB	0 B
build/rich-text/index.js	14.4 kB	0 B
build/server-side-render/index.js	2.55 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	4.01 kB	0 B
build/viewport/index.js	1.61 kB	0 B
build/warning/index.js	1.14 kB	0 B
build/wordcount/index.js	1.18 kB	0 B

_{compressed-size-action}

[draganescu]

Howdy, I tested this and the current PR does allow the toolbar to be visible.