Editor: Register core blocks on the server

Exposes all core blocks (excluding embeds) on the server to be used with the REST API block types endpoint.

Props spacedmonkey, timothyblynjacobs.
Fixes #50263.



git-svn-id: https://develop.svn.wordpress.org/trunk@48262 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/blocks/missing/block.json

@@ -0,0 +1,23 @@
+{
+	"name": "core/missing",
+	"category": "text",
+	"attributes": {
+		"originalName": {
+			"type": "string"
+		},
+		"originalUndelimitedContent": {
+			"type": "string"
+		},
+		"originalContent": {
+			"type": "string",
+			"source": "html"
+		}
+	},
+	"supports": {
+		"className": false,
+		"customClassName": false,
+		"inserter": false,
+		"html": false,
+		"reusable": false
+	}
+}