fix(schematics): sidenav toolbar should use default background (#13282)

Author: Splaktar

src/lib/schematics/nav/files/__path__/__name@dasherize@if-flat__/__name@dasherize__.component.__styleext__

@@ -6,6 +6,10 @@
   width: 200px;
 }
 
+.sidenav .mat-toolbar {
+  background: inherit;
+}
+
 .mat-toolbar.mat-primary {
   position: sticky;
   top: 0;

src/lib/schematics/nav/files/__path__/__name@dasherize@if-flat__/__name@dasherize__.component.html

@@ -6,7 +6,7 @@
     [attr.role]="(isHandset$ | async) ? 'dialog' : 'navigation'"
     [mode]="(isHandset$ | async) ? 'over' : 'side'"
     [opened]="!(isHandset$ | async)">
-    <mat-toolbar color="primary">Menu</mat-toolbar>
+    <mat-toolbar>Menu</mat-toolbar>
     <mat-nav-list>
       <a mat-list-item href="#">Link 1</a>
       <a mat-list-item href="#">Link 2</a>