Changeset 48141 for trunk/tests/phpunit/tests/blocks/fixtures/block.json

Editor: Introduce new API method that register block from block.json metadata file

Backports changes added to Gutenberg in:

• ​https://github.com/WordPress/gutenberg/pull/20794
• ​https://github.com/WordPress/gutenberg/pull/22519

register_block_type_from_metadata function is going to be used to register all blocks on the server using block.json metadata files.

Props ocean90, azaozz, aduth, mcsf, jorgefilipecosta, spacedmonkey, nosolosw, swissspidy and noahtallen.
Fixes #50263.