Bump plugin version to 5.5

[talldan]

Changelog

Features

• Add a new Group block.
• Add vertical alignment support to the Media & Text block.
• Add the image fill option to the Media & Text block.

Enhancements

• Improvements to the Image Block flows.
• Automatically add mailto: to email addresses when linking.
• Add visual handles for side resizers for various blocks.
• Improve the performance of the annotations by avoiding excessive memoization.
• Announce the color accessibility issues to screen readers.
• Add enum block attributes validation to browser block parser.
• Use a consistent grey background in the Shortcode block.
• Improve accessibility of video block select poster image.
• Respect prefers-reduced-motion for fixed backgrounds in Cover block.
• Prevent ArrowLeft key press in multi-line selection from prematurely triggering multi-selection.

Bug Fixes

• Avoid keeping the RichText value in cache indefinitely.
• Fix the post title input borders in the code editor.
• Fix the block restrictions to insert, replace or move blocks.
• Select gallery images on focus.
• Fix removing gallery images on delete/backspace key press.
• Fix small visual regression in the block autocompete popover.
• Fix the data module resolver resolution status.
• Avoid saving metaboxes when previewing changes.
• Fix selecting the separator block.
• Fix displaying the color palette tooltips on hover.
• Fix Firefox/NVDA bug not announcing the toggle settings button.
• Fix arrow navigation in paragraph blocks with backgrounds.
• Fix the columns block click to select.
• Fix post dirtiness after fetching reusable blocks.
• Fix the hover and focus styles for buttons with the isBusy prop.
• Remove the box shadow from the side inserter button.
• Changing the region navigation shortcuts to avoid conflicts.
• Fix space insertion in the Button block in Firefox.
• Prevent the link popover from animating constantly as we type. 
• Fix the warning triggered by clearing the height of the spacer block.
• Fix undo behavior after fresh post loading.

Documentation

• Add design documentation to the Modal component.
• Clarify the CSS naming coding guidelines.
• Add InspectorControls usage example.
• Tweaks and typos: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13.

Various

• Bootstrap the design of the new widgets screen (non functional yet).
• Reorganization of the block-library code base:
  • Use a babel plugin to load block.json files.
  • Introduce block.json metadata for all client side blocks.
  • Move the edit functions and the icons to separate files.
  • Move the transforms and save functions to separate files.
• Add forwardRef support to the PlainText component.
• Support Button Block Appender in the InnerBlocks component.
• Unset the focal point attributes from the Cover block if not needed.
• Consistently return promises from the data module action calls.
• Remove obsolete CSS currentColor usage.
• Improve the e2e test CLI arguments and docs.
• Improve the e2e test login stability on MacOS.
• Remove is-plain-obj package dependency.
• Remove invalid urls and ids from media test fixtures.
• Remove the deprecated Gutenberg plugin functions slated for 5.4 and 5.5.
• remove or rename undocumented RichText package functions and constants.
• Adjust paragraph block spacing to use standardised variables.
• Allow spaces in file paths for package build process. 
• Update pre-commit to check modified files only.
• Improve the performance of the webpack build configuration.
• Update dependencies with known vulnerabilities.
• Fix typo in variable names.

Mobile

• Accessibility improvements to the Button component.
• Enhance the unsupported block type. 
• Fix image upload progress not being displayed consistently.
• Support copy/pasting images.
• Add the list block.
• Visual refinements for the native nextpage block.
• Fix importing the column block.
• Remove DOM logic from the list block toolbar.
• Put the caret at the end of the text field after merging blocks.
• Fix caret position after inline paste.

[ntwb]

LGTM 👍

[talldan]

Had some issues with tests passing on this branch. In particular the undo › Should undo to expected level intervals e2e test failed three times consecutively.

@youknowriad gave the ok to merge the PR without a passing test. We did previously have passing tests on the 5.5 release candidate PR, which is exactly the same as this apart from the version bump, so this seems to be a problematic test.

A fix for the issue is apparently in hand. Further details on the problem can be found in this comment - #14955 (comment).