Create block: Add support for format:js to ESNext template

[gziolo]

Description

This PR adds support for format:js script to the block scaffolded when using the default ESNext template.

It also runs this command during the scaffolding process. The reason for that is that we can't predict the length of inputs provided by users so we can't really format JavaScript file correctly for all cases. That's why the idea to format those files popped up. It ensures that users won't see any errors when running npm run lint:js in the scaffolded project. At the moment, when I run npm ini @wordpress/block, use default values and run npm run lint:js in the scaffolded folder, I see:

/Users/gziolo/Projects/gutenberg/esnext-example/src/index.js
  25:12  error  Replace `⏎↹↹'ESNext·Example',⏎↹↹'create-block'⏎↹` with `·'ESNext·Example',·'create-block'·`                                                                           prettier/prettier
  72:10  error  Replace `·'ESNext·Example·–·hello·from·the·editor!',·'create-block'·` with `⏎↹↹↹↹↹'ESNext·Example·–·hello·from·the·editor!',⏎↹↹↹↹↹'create-block'⏎↹↹↹↹`                prettier/prettier
  88:10  error  Replace `·'ESNext·Example·–·hello·from·the·saved·content!',·'create-block'·` with `⏎↹↹↹↹↹'ESNext·Example·–·hello·from·the·saved·content!',⏎↹↹↹↹↹'create-block'⏎↹↹↹↹`  prettier/prettier

✖ 3 problems (3 errors, 0 warnings)
  3 errors and 0 warnings potentially fixable with the `--fix` option.

How has this been tested?

$ npx wp-create-block
$ cd esnext-example
$ npm run lint:js
$ npm run format:js

Types of changes

Enhancement

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.

[github-actions]

Size Change: 0 B

Total Size: 861 kB

ℹ️ View Unchanged

Filename	Size	Change
build/a11y/index.js	1.01 kB	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	104 kB	0 B
build/block-editor/style-rtl.css	9.78 kB	0 B
build/block-editor/style.css	9.77 kB	0 B
build/block-library/editor-rtl.css	7.67 kB	0 B
build/block-library/editor.css	7.67 kB	0 B
build/block-library/index.js	114 kB	0 B
build/block-library/style-rtl.css	7.47 kB	0 B
build/block-library/style.css	7.48 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	57.6 kB	0 B
build/components/index.js	190 kB	0 B
build/components/style-rtl.css	16.1 kB	0 B
build/components/style.css	16 kB	0 B
build/compose/index.js	5.76 kB	0 B
build/core-data/index.js	10.5 kB	0 B
build/data-controls/index.js	1.04 kB	0 B
build/data/index.js	8.22 kB	0 B
build/date/index.js	5.36 kB	0 B
build/deprecated/index.js	771 B	0 B
build/dom-ready/index.js	569 B	0 B
build/dom/index.js	3.06 kB	0 B
build/edit-post/index.js	90.7 kB	0 B
build/edit-post/style-rtl.css	8.69 kB	0 B
build/edit-post/style.css	8.68 kB	0 B
build/edit-site/index.js	2.71 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	4.36 kB	0 B
build/edit-widgets/style-rtl.css	2.8 kB	0 B
build/edit-widgets/style.css	2.79 kB	0 B
build/editor/editor-styles-rtl.css	327 B	0 B
build/editor/editor-styles.css	328 B	0 B
build/editor/index.js	45.1 kB	0 B
build/editor/style-rtl.css	4.13 kB	0 B
build/editor/style.css	4.11 kB	0 B
build/element/index.js	4.45 kB	0 B
build/escape-html/index.js	733 B	0 B
build/format-library/index.js	7.6 kB	0 B
build/format-library/style-rtl.css	500 B	0 B
build/format-library/style.css	501 B	0 B
build/hooks/index.js	1.92 kB	0 B
build/html-entities/index.js	621 B	0 B
build/i18n/index.js	3.45 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	1.68 kB	0 B
build/list-reusable-blocks/index.js	2.99 kB	0 B
build/list-reusable-blocks/style-rtl.css	215 B	0 B
build/list-reusable-blocks/style.css	216 B	0 B
build/media-utils/index.js	4.84 kB	0 B
build/notices/index.js	1.57 kB	0 B
build/nux/index.js	3.02 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	1.49 kB	0 B
build/priority-queue/index.js	878 B	0 B
build/redux-routine/index.js	2.84 kB	0 B
build/rich-text/index.js	14.3 kB	0 B
build/server-side-render/index.js	2.54 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 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

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