MDL-73611 theme_boost: restore scroll on drawers div

theme/boost/scss/moodle/layout.scss

@@ -188,6 +188,7 @@
 
     #page.drawers {
         position: relative;
+        overflow-y: auto;
         @include transition(0.2s);
         height: calc(100vh - #{$navbar-height});
         margin-top: $navbar-height;

theme/boost/style/moodle.css

@@ -20379,6 +20379,7 @@ span[data-flexitour="container"][x-placement="right"], span[data-flexitour="cont
     height: calc(100vh - 60px); }
   #page.drawers {
     position: relative;
+    overflow-y: auto;
     transition: 0.2s;
     height: calc(100vh - 60px);
     margin-top: 60px;

theme/classic/style/moodle.css

@@ -20325,6 +20325,7 @@ span[data-flexitour="container"][x-placement="right"], span[data-flexitour="cont
     height: calc(100vh - 50px); }
   #page.drawers {
     position: relative;
+    overflow-y: auto;
     transition: 0.2s;
     height: calc(100vh - 50px);
     margin-top: 50px;