General: Add block_hooks field to block type registration, REST API.

In order to implement Block Hooks, we need to add a new `block_hooks` field to the `WP_Block_Type` class, as well as to block registration related functions, the block types REST API controller, etc.

Props gziolo.
Fixes #59346. See #59313.

git-svn-id: https://develop.svn.wordpress.org/trunk@56587 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/data/blocks/notice/block.json

@@ -30,6 +30,9 @@
 	"selectors": {
 		"root": ".wp-block-notice"
 	},
+	"blockHooks": {
+		"core/post-content": "before"
+	},
 	"supports": {
 		"align": true,
 		"lightBlockWrapper": true