Blocks: Add support for variations in block.json` file

We integrated variations with block types and the corresponding REST API endpoint in #52688. It's a follow-up patch to add missing support to the `block.json` metadata file when using `register_block_type`.

Some fields for variations are translatable.Therefore, i18n schema was copied over from Gutenberg: https://github.com/WordPress/gutenberg/blob/trunk/packages/blocks/src/api/i18n-block.json. The accompanying implementation was adapted as `translate_settings_using_i18n_schema`.

Props: gwwar, swissspidy, schlessera, jorgefilipecosta.
Fixes #53238.



git-svn-id: https://develop.svn.wordpress.org/trunk@51599 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/functions.php

@@ -1037,6 +1037,31 @@ class Tests_Functions extends WP_UnitTestCase {
 		$this->assertFalse( $json );
 	}
 
+	/**
+	 * @ticket 53238
+	 */
+	function test_wp_json_file_decode() {
+		$result = wp_json_file_decode(
+			DIR_TESTDATA . '/blocks/notice/block.json'
+		);
+
+		$this->assertIsObject( $result );
+		$this->assertSame( 'tests/notice', $result->name );
+	}
+
+	/**
+	 * @ticket 53238
+	 */
+	function test_wp_json_file_decode_associative_array() {
+		$result = wp_json_file_decode(
+			DIR_TESTDATA . '/blocks/notice/block.json',
+			array( 'associative' => true )
+		);
+
+		$this->assertIsArray( $result );
+		$this->assertSame( 'tests/notice', $result['name'] );
+	}
+
 	/**
 	 * @ticket 36054
 	 * @dataProvider datetime_provider