I18N: Add context for some Media Library filter strings:

* Audio
* Video
* Unattached

This allows for more homogeneous translations in languages where keeping a plural form is important.

Follow-up to [6910], [7397], [8901], [9556], [11749], [13100], [12110], [15491], [15578], [22743], [29426], [29625], [34256], [45651], [46437].

Props jdy68, audrasjb, SergeyBiryukov.
Fixes #54238.

git-svn-id: https://develop.svn.wordpress.org/trunk@51903 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/post.php

@@ -2939,7 +2939,7 @@ function get_post_mime_types() {
 			),
 		),
 		'audio'       => array(
-			__( 'Audio' ),
+			_x( 'Audio', 'file type group' ),
 			__( 'Manage Audio' ),
 			/* translators: %s: Number of audio files. */
 			_n_noop(
@@ -2948,7 +2948,7 @@ function get_post_mime_types() {
 			),
 		),
 		'video'       => array(
-			__( 'Video' ),
+			_x( 'Video', 'file type group' ),
 			__( 'Manage Video' ),
 			/* translators: %s: Number of video files. */
 			_n_noop(