fix(toast): exclude igx-icon from typography styles (#16791)

Fixes issue where Material icons in toast were not displayed correctly.
Typography styles were being applied to all child elements including icons,
which interfered with icon rendering. Now explicitly excludes igx-icon
elements from typography styles using :not() selector.

Closes #16760

Author: simeonoff

projects/igniteui-angular/src/lib/core/styles/components/toast/_toast-theme.scss

@@ -52,7 +52,7 @@
     $text: map.get($categories, 'text');
 
     %igx-toast-display,
-    %igx-toast-display > * {
+    %igx-toast-display > *:not(igx-icon) {
         @include type-style($text) {
             margin: 0;
         }