Twenty Twenty-One: Correct default image alignment in the editor.

By default, the theme centers images on the front end when no alignment is selected. In the editor, however, images were aligned to the left side of the block.

This commit ensures that the alignment in the editor matches the one on the front end.

Props sabernhardt, ashfame, poena, annezazu.
Fixes #53809.

git-svn-id: https://develop.svn.wordpress.org/trunk@52142 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-content/themes/twentytwentyone/assets/css/ie-editor.css

@@ -1458,6 +1458,7 @@ h6 {
 }
 
 /* Center image block by default in the editor */
+.wp-block-image,
 .wp-block-image > div {
 	text-align: center;
 }

src/wp-content/themes/twentytwentyone/assets/css/style-editor.css

@@ -1127,6 +1127,7 @@ h6,
 }
 
 /* Center image block by default in the editor */
+.wp-block-image,
 .wp-block-image > div {
 	text-align: center;
 }

src/wp-content/themes/twentytwentyone/assets/sass/05-blocks/image/_editor.scss

@@ -1,5 +1,6 @@
 /* Center image block by default in the editor */
 
+.wp-block-image,
 .wp-block-image > div {
 	text-align: center;
 }