Extract block mover buttons so that they can be individually imported

[talldan]

Description

The Block mover buttons are exported as a single component. This PR allows the up and down buttons to be individually imported.

This change is required as part of #18014, which manages focus on the buttons using a roving tab index within the block navigator.

How has this been tested?

This is just a refactor, so no changes. Block movers should continue to look and work as they currently do.

Types of changes

Refactor

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: +198 B (0%)

Total Size: 821 kB

Filename	Size	Change
build/block-editor/index.js	101 kB	+187 B (0%)
build/block-editor/style-rtl.css	10.2 kB	+6 B (0%)
build/block-editor/style.css	10.2 kB	+5 B (0%)

ℹ️ View Unchanged

Filename	Size	Change
build/a11y/index.js	1.02 kB	0 B
build/annotations/index.js	3.62 kB	0 B
build/api-fetch/index.js	4.08 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	6.6 kB	0 B
build/block-directory/style-rtl.css	760 B	0 B
build/block-directory/style.css	761 B	0 B
build/block-library/editor-rtl.css	7.08 kB	0 B
build/block-library/editor.css	7.08 kB	0 B
build/block-library/index.js	115 kB	0 B
build/block-library/style-rtl.css	7.24 kB	0 B
build/block-library/style.css	7.25 kB	0 B
build/block-library/theme-rtl.css	683 B	0 B
build/block-library/theme.css	685 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	48.1 kB	0 B
build/components/index.js	179 kB	0 B
build/components/style-rtl.css	16.9 kB	0 B
build/components/style.css	16.9 kB	0 B
build/compose/index.js	6.66 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	3.1 kB	0 B
build/edit-navigation/index.js	4.05 kB	0 B
build/edit-navigation/style-rtl.css	485 B	0 B
build/edit-navigation/style.css	485 B	0 B
build/edit-post/index.js	28.1 kB	0 B
build/edit-post/style-rtl.css	12.2 kB	0 B
build/edit-post/style.css	12.2 kB	0 B
build/edit-site/index.js	12.3 kB	0 B
build/edit-site/style-rtl.css	5.19 kB	0 B
build/edit-site/style.css	5.2 kB	0 B
build/edit-widgets/index.js	8.37 kB	0 B
build/edit-widgets/style-rtl.css	4.68 kB	0 B
build/edit-widgets/style.css	4.68 kB	0 B
build/editor/editor-styles-rtl.css	428 B	0 B
build/editor/editor-styles.css	431 B	0 B
build/editor/index.js	44.3 kB	0 B
build/editor/style-rtl.css	5.07 kB	0 B
build/editor/style.css	5.08 kB	0 B
build/element/index.js	4.65 kB	0 B
build/escape-html/index.js	734 B	0 B
build/format-library/index.js	7.63 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	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	3.13 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/plugins/index.js	2.56 kB	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	2.67 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	4.02 kB	0 B
build/viewport/index.js	1.84 kB	0 B
build/warning/index.js	1.14 kB	0 B
build/wordcount/index.js	1.18 kB	0 B

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[mtias]

Do you think this still makes sense considering possible work in #21935 ?

[adamziel]

The code looks good and works well so I'm approving. I'll leave the decision whether or not to merge this (as per the previous comment) up to @talldan .

[talldan]

@mtias I don't see much difference in #21935, the buttons in the movers would still need to have their focus managed individually.

Having said that, there's some parallel work being done on the toolbar that has similar goals, but addresses this differently - #20008.

(cc @diegohaz - it looks like our changes will conflict, this PR is to support mover buttons in the Block Navigator where they wouldn't be ToolbarButtons. I think we should be able to make our code work together. We could consider something like <BlockMoverButton as={ ToolbarButton } /> and also expose that for the BlockMover component, or make ToolbarButton the default and make it work the other way around, that would make sense).

[talldan]

I've tested the PR again, and I can't see any issues.

I'm going to move forward and merge this, it's a low risk change.