wp-env: add mu-plugins support

[noahtallen]

Description

Adds support to .wp-env.json for mu-plugins. (Accepted sources work the same as themes & plugins.)

How has this been tested?

Locally and with unit tests

Types of changes

New feature

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: 0 B

Total Size: 825 kB

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	6.61 kB	0 B
build/block-directory/style-rtl.css	760 B	0 B
build/block-directory/style.css	761 B	0 B
build/block-editor/index.js	102 kB	0 B
build/block-editor/style-rtl.css	10.3 kB	0 B
build/block-editor/style.css	10.3 kB	0 B
build/block-library/editor-rtl.css	7.12 kB	0 B
build/block-library/editor.css	7.12 kB	0 B
build/block-library/index.js	115 kB	0 B
build/block-library/style-rtl.css	7.38 kB	0 B
build/block-library/style.css	7.38 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	180 kB	0 B
build/components/style-rtl.css	17 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	8.45 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	4.41 kB	0 B
build/edit-navigation/style-rtl.css	618 B	0 B
build/edit-navigation/style.css	617 B	0 B
build/edit-post/index.js	28 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	12.1 kB	0 B
build/edit-site/style-rtl.css	5.22 kB	0 B
build/edit-site/style.css	5.22 kB	0 B
build/edit-widgets/index.js	8.37 kB	0 B
build/edit-widgets/style-rtl.css	4.69 kB	0 B
build/edit-widgets/style.css	4.69 kB	0 B
build/editor/editor-styles-rtl.css	425 B	0 B
build/editor/editor-styles.css	428 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	2.14 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	3.12 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	2.68 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

_{compressed-size-action}

[epiqueras]

Doesn't #22256 remove the need for this? MU Plugins can just go in mappings, and we can keep the schema simple.

[noahtallen]

Sure. but why wouldn't we remove plugins and themes in that scenario? If the plugins/themes API is being kept because it's an easy-to-use API and not just for back-compat, then why wouldn't we support mu-plugins in that easy-to-use API as well? Unless we consider mu-plugins more of an advanced use case, I guess.

[epiqueras]

MU Plugins are an advanced use case, and they don't need activation.

[noahtallen]

don't need activation

Right, how does that relate though? wp-env isn't trying to activate them. I'm definitely fine just using #22256 instead. 🤷 We can always reopen this if people really want mu-plugins as a more simple API.

[epiqueras]

Because the main benefit of having explicit plugins and themes fields is that we can activate them for the user, if mu-plugins don't need that, there is little value in adding it as a new field.

[noahtallen]

Ah, I see the argument.