fix(material/radio): Apply tokens at mixin root

Applies radio tokens at the theme mixin's root selector (or html if the mixin
is called with no selector). This makes it easier for users to override tokens
without worrying about specificity.

src/material/radio/_radio-theme.scss

@@ -1,7 +1,7 @@
-@use '@material/radio/radio' as mdc-radio;
 @use '@material/radio/radio-theme' as mdc-radio-theme;
 @use '@material/form-field' as mdc-form-field;
 @use '../core/mdc-helpers/mdc-helpers';
+@use '../core/style/sass-utils';
 @use '../core/theming/theming';
 @use '../core/theming/inspection';
 @use '../core/tokens/token-utils';
@@ -10,7 +10,7 @@
 @use '../core/tokens/m2/mat/radio' as tokens-mat-radio;
 
 @mixin base($theme) {
-  .mat-mdc-radio-button {
+  @include sass-utils.current-selector-or-root() {
     @include mdc-radio-theme.theme(tokens-mdc-radio.get-unthemable-tokens());
     @include token-utils.create-token-values(
         tokens-mat-radio.$prefix, tokens-mat-radio.get-unthemable-tokens());
@@ -19,7 +19,7 @@
 
 @mixin color($theme) {
   @include mdc-helpers.using-mdc-theme($theme) {
-    .mat-mdc-radio-button {
+    @include sass-utils.current-selector-or-root() {
       @include mdc-form-field.core-styles($query: mdc-helpers.$mdc-theme-styles-query);
     }
   }
@@ -46,7 +46,7 @@
 }
 
 @mixin typography($theme) {
-  .mat-mdc-radio-button {
+  @include sass-utils.current-selector-or-root() {
     @include mdc-radio-theme.theme(tokens-mdc-radio.get-typography-tokens($theme));
     @include mdc-helpers.using-mdc-typography($theme) {
       @include mdc-form-field.core-styles($query: mdc-helpers.$mdc-typography-styles-query);
@@ -57,7 +57,7 @@
 @mixin density($theme) {
   $density-scale: inspection.get-theme-density($theme);
 
-  .mat-mdc-radio-button .mdc-radio {
+  @include sass-utils.current-selector-or-root() {
     @include mdc-radio-theme.theme(tokens-mdc-radio.get-density-tokens($theme));
   }