Hide drawers if empty.

src/scss/drawer-inject.scss

@@ -22,7 +22,6 @@
 #d {
   // Need to allow drawer controls to be visible.
   overflow: visible;
-  visibility: visible;
 }
 
 :host([location=right]) #d {

src/scss/drawer.scss

@@ -27,6 +27,12 @@ div.control-surround {
   }
   right: 100%;
 }
+:host([empty]), :host([empty]) > * {
+  visibility: hidden;
+}
+:host(:not([empty])), :host(:not([empty])) > * {
+  visibility: visible;
+}
 
 ha-icon.control {
   color: var(--secondary-color, white);