Fix: Custom gradient picker unable to change predefined gradients with hex colors

[jorgefilipecosta]

This PR makes the custom gradient picker able to change predefined gradients with colors defined in hexadecimal format.

Continues the work started on #23363.

Description

I added this code block to the functions.php file of the current enabled theme:

add_theme_support(
	'editor-gradient-presets',
	array(
		array(
			'name'     => __( 'Hex gradient', 'themeslug'  ),
			'gradient' => 'linear-gradient(to bottom, #000000 0%, #fff 100%)',
			'slug'     => 'hex-gradient',
		),
	)
);

I added a group block. I set the background of the group to the predefined gradient, and I verified I was able to change the gradient correctly with the custom gradient picker (on master it reverts to the default gradient). The predefined gradient will not preview accurately on the block unless the gradient class is added to the theme.

[github-actions]

Size Change: +1 B

Total Size: 1.16 MB

Filename	Size	Change
build/components/index.js	200 kB	+1 B

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	7.97 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	125 kB	0 B
build/block-editor/style-rtl.css	10.6 kB	0 B
build/block-editor/style.css	10.6 kB	0 B
build/block-library/editor-rtl.css	7.59 kB	0 B
build/block-library/editor.css	7.59 kB	0 B
build/block-library/index.js	132 kB	0 B
build/block-library/style-rtl.css	7.76 kB	0 B
build/block-library/style.css	7.77 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	48.4 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	8.45 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	3.23 kB	0 B
build/edit-navigation/index.js	10.9 kB	0 B
build/edit-navigation/style-rtl.css	1.08 kB	0 B
build/edit-navigation/style.css	1.08 kB	0 B
build/edit-post/index.js	304 kB	0 B
build/edit-post/style-rtl.css	5.62 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	9.38 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	7.72 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	2.71 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

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