fix(input): address input related issues

- Restore the missing Material line-type corner radius on the
Combo/Select toggle button and stretch consumer-supplied buttons to fill
the Fluent input's full height in prefix/suffix slots.
- Move themed()'s emission from the ig.components layer to ig.base

Author: simeonoff

projects/igniteui-angular/core/src/core/styles/themes/_scoping.scss

@@ -25,7 +25,7 @@
 @mixin themed($theme, $variant: null) {
     $_theme: '' + $theme;
 
-    @include layer(components) {
+    @include layer(base) {
         @if $variant {
             @container style(--ig-theme: #{$_theme}) and style(--ig-theme-variant: #{$variant}) {
                 @content;

projects/igniteui-angular/core/src/core/styles/themes/generators/_base.scss

@@ -119,7 +119,7 @@
         $excluded: is-component($exclude);
     }
 
-    @layer ig.base, ig.typography, ig.components, ig.derived;
+    @layer ig.base, ig.typography, ig.derived;
 
     // Component tokens — emitted once per theme, gated by $exclude so a
     // consumer that only uses a handful of components isn't paying for the

projects/igniteui-angular/input-group/src/input-group/themes/shared/fluent.scss

@@ -57,6 +57,19 @@ $_theme: digest-schema($fluent-input-group);
         }
     }
 
+    igx-prefix,
+    [igxPrefix],
+    igx-suffix,
+    [igxSuffix] {
+        // Stretch consumer-supplied buttons to fill the taller Fluent bundle height
+        button,
+        [igxButton],
+        [igxIconButton] {
+            border-radius: 0;
+            height: 100%;
+        }
+    }
+
     @include e(bundle-start) {
         overflow: hidden;
         border-start-start-radius: var-get($_theme, 'border-border-radius');

projects/igniteui-angular/input-group/src/input-group/themes/shared/material.scss

@@ -85,6 +85,14 @@ $input-bottom-spacing: rem(6px);
             grid-column: 1 / -1;
         }
 
+        @include e(bundle-start) {
+            border-start-start-radius: calc(var-get($_theme, 'box-border-radius') - rem(1px));
+        }
+
+        @include e(bundle-end) {
+            border-start-end-radius: calc(var-get($_theme, 'box-border-radius') - rem(1px));
+        }
+
         @include e(bundle-main) {
             padding-inline: $input-inline-padding;
             grid-column: 2;