docs(multiple): adds screen reader friendly tooltip to hamburger icon

Updates dev-app layout hamburger icon button to use a matTooltip similarly to other icon config
buttons in the header. This adds a visible tooltip for sighted users as well as an announced
screen reader value when focusing on the hamburger button.

Fixes b/435497550

Author: essjay05

src/dev-app/dev-app/dev-app-layout.html

@@ -35,7 +35,10 @@
   <main [attr.dir]="state.direction" [class]="getDensityClass()" class="demo-main">
     <!-- The toolbar should always be in the LTR direction -->
     <mat-toolbar color="primary" dir="ltr">
-      <button matIconButton (click)="navigation.open('mouse')">
+      <button
+        matIconButton
+        matTooltip="{{ navigation.opened ? 'Close' : 'Open'}} Navigation Menu"
+        (click)="navigation.open('mouse')">
         <mat-icon>menu</mat-icon>
       </button>
       <div class="demo-toolbar">