Add padding to the side-by-side diff so the scroll bar doesn't cover the code (#1209)

Author: frankdekker

assets/styles/review-file-diff-side-by-side.scss

@@ -17,5 +17,6 @@
 
 .diff-side-by-side__diff-block {
     min-width: 100%;
+    padding-bottom: 10px;
     width: max-content;
 }