Blocks: Add i18n support to register_block_type_from_metadata

Related Gutenberg issue: https://github.com/WordPress/gutenberg/issues/23636.
Related WP-CLI PR: https://github.com/wp-cli/i18n-command/pull/210.
Related documentation proposal: https://github.com/WordPress/gutenberg/blob/master/docs/designers-developers/developers/block-api/block-metadata.md#internationalization-not-implemented

Adds programatic i18n support to `register_block_type_from_metadata` function for block settings registered from `block.json` file that provides `textdomain` field.


Props swissspidy, ocean90.
Fixes #52301.



git-svn-id: https://develop.svn.wordpress.org/trunk@49981 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/data/blocks/notice/block.asset.php

@@ -0,0 +1,6 @@
+<?php
+
+return array(
+	'dependencies' => array(),
+	'version'      => 'test',
+);

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

@@ -0,0 +1 @@
+/* Test CSS file */

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

@@ -0,0 +1 @@
+/* Test JavaScript file. */

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

@@ -0,0 +1,53 @@
+{
+	"apiVersion": 2,
+	"name": "tests/notice",
+	"title": "Notice",
+	"category": "common",
+	"parent": [
+		"core/group"
+	],
+	"providesContext": {
+		"tests/message": "message"
+	},
+	"usesContext": [
+		"groupId"
+	],
+	"icon": "star",
+	"description": "Shows warning, error or success notices…",
+	"keywords": [
+		"alert",
+		"message"
+	],
+	"textdomain": "notice",
+	"attributes": {
+		"message": {
+			"type": "string",
+			"source": "html",
+			"selector": ".message"
+		}
+	},
+	"supports": {
+		"align": true,
+		"lightBlockWrapper": true
+	},
+	"styles": [
+		{
+			"name": "default",
+			"label": "Default",
+			"isDefault": true
+		},
+		{
+			"name": "other",
+			"label": "Other"
+		}
+	],
+	"example": {
+		"attributes": {
+			"message": "This is a notice!"
+		}
+	},
+	"editorScript": "tests-notice-editor-script",
+	"script": "tests-notice-script",
+	"editorStyle": "tests-notice-editor-style",
+	"style": "tests-notice-style"
+}