I18N: Improve translator comments.

* Add missing translator comments.
* Fix placement of some translator comments. Translator comments should be on the line directly above the line containing the translation function call for optimal compatibility with various `.pot` file generation tools. The CS auto-fixing, which changed some inconsistent function calls to multi-line function calls, is part of the reason why this was no longer the case for a select group of translator comments.

Includes minor code layout fixes.

Polyglots, rejoice! All WordPress core files now have translator comments for all strings with placeholders!

Props jrf, subrataemfluence, GaryJ, webdados, Dency, swissspidy, alvarogois, marcomartins, mihaiiceyro, vladwtz, niq1982, flipkeijzer, michielatyoast, chandrapatel, thrijith, joshuanoyce, FesoVik, tessak22, bhaktirajdev, cleancoded, dhavalkasvala, garrett-eclipse, bibliofille, socalchristina, priyankkpatel, 5hel2l2y, adamsilverstein, JeffPaul, pierlo, SergeyBiryukov.
Fixes #44360.
Built from https://develop.svn.wordpress.org/trunk@45926


git-svn-id: http://core.svn.wordpress.org/trunk@45737 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/rest-api.php

@@ -1177,6 +1177,7 @@ function rest_validate_value_from_schema( $value, $args, $param = '' ) {
 				}
 			} elseif ( isset( $args['additionalProperties'] ) ) {
 				if ( false === $args['additionalProperties'] ) {
+					/* translators: %s: property of an object */
 					return new WP_Error( 'rest_invalid_param', sprintf( __( '%1$s is not a valid property of Object.' ), $property ) );
 				}