This commit improves PHP performance for core blocks by reading a single PHP file with block metadata, instead of reading a JSON file per-block and then decoding from JSON to PHP.
Includes:
* Adding a new Grunt task to convert `block.json` files to `block-json.php`.
* Using the new `block-json.php` file in the `register_block_type_from_metadata()` function.
Follow-up to [48141].
Props aristath, gziolo, johnbillion, presstoke, mukesh27, hellofromTonya, petitphp, adamsilverstein, costdev, desrosj, SergeyBiryukov.
Fixes#55005.
Built from https://develop.svn.wordpress.org/trunk@54276
git-svn-id: http://core.svn.wordpress.org/trunk@53835 1a063a9b-81f0-0310-95a4-ce76da25c4cd
