Code comments improvements (#15722)

- Right-align the Reply and Resolve buttons
- Center Resolved text and add some padding
- Add padding to inline comments
- Indent the comment content to align with author name
- Re-parent form to allow better button layout space.

Co-authored-by: zeripath <art27@cantab.net>

web_src/less/_review.less

@@ -112,14 +112,10 @@
       display: block;
     }
   }
+}
 
-  button.comment-form-reply {
-    margin: .5em .5em .5em 4.5em;
-  }
-
-  form.comment-form-reply {
-    margin: 0 0 0 1em;
-  }
+.diff-file-body .comment-form {
+  margin: 0 0 0 3em;
 }
 
 .file-comment {