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.


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