E2E tests: Block variations

[gziolo]

Description

Part of #16283.

This PR adds 5 new E2E tests that cover new block variations API. It includes a custom WordPress plugin that registers 3 sets of block variations:

1. Adds a variation that overrides the default Quote block type with a non-default style variation.
2. Adds two additional variations to the Paragraph block type with some custom initial attributes.
3. Adds additional variation to the Columns block that is rendered in the variation picker after the block is inserted in the editor. It means it's scoped to the block only.

How has this been tested?

npm run test-e2e packages/e2e-tests/specs/editor/plugins/block-variations.js

Types of changes

New e2e tests, no production changes.

Checklist:

• My code is tested.
• My code follows the WordPress code style.

[github-actions]

Size Change: 0 B

Total Size: 859 kB

ℹ️ View Unchanged

Filename	Size	Change
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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
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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	8.23 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	568 B	0 B
build/dom/index.js	3.06 kB	0 B
build/edit-post/index.js	90.5 kB	0 B
build/edit-post/style-rtl.css	8.69 kB	0 B
build/edit-post/style.css	8.68 kB	0 B
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build/edit-site/style.css	2.62 kB	0 B
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build/edit-widgets/style.css	2.79 kB	0 B
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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	622 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	2.24 kB	0 B
build/primitives/index.js	1.49 kB	0 B
build/priority-queue/index.js	878 B	0 B
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build/rich-text/index.js	14.3 kB	0 B
build/server-side-render/index.js	2.54 kB	0 B
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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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[mcsf]

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