fix(material/button-toggle): move unthemable tokens to theme mixin (#27883)

Though these tokens are not currently affected by the theme, in the
future they will be affected by the design system used for theming (M2
or M3)

BREAKING CHANGE:
There are new styles emitted by mat.button-toggle-theme that are not
emitted by any of: mat.button-toggle-color, mat.button-toggle-typography,
mat.button-toggle-density. If you rely on the partial mixins only and don't
call mat.button-toggle-theme, you can add mat.button-toggle-base to get the
missing styles.

Author: mmalerba

src/material/_index.scss

@@ -77,7 +77,7 @@
 @forward './button/icon-button-theme' as icon-button-* show icon-button-color,
   icon-button-typography, icon-button-density, icon-button-theme;
 @forward './button-toggle/button-toggle-theme' as button-toggle-* show button-toggle-theme,
-  button-toggle-color, button-toggle-typography, button-toggle-density;
+  button-toggle-color, button-toggle-typography, button-toggle-density, button-toggle-base;
 @forward './card/card-theme' as card-* show card-theme, card-color, card-typography, card-density,
   card-base;
 @forward './checkbox/checkbox-theme' as checkbox-* show checkbox-theme, checkbox-color,

src/material/button-toggle/_button-toggle-theme.scss

@@ -6,6 +6,19 @@
 @use '../core/tokens/token-utils';
 @use '../core/style/sass-utils';
 
+@mixin base($theme) {
+  @include sass-utils.current-selector-or-root() {
+    @include token-utils.create-token-values(
+        tokens-mat-legacy-button-toggle.$prefix,
+        tokens-mat-legacy-button-toggle.get-unthemable-tokens()
+    );
+    @include token-utils.create-token-values(
+        tokens-mat-standard-button-toggle.$prefix,
+        tokens-mat-standard-button-toggle.get-unthemable-tokens()
+    );
+  }
+}
+
 @mixin color($theme) {
   @include sass-utils.current-selector-or-root() {
     @include token-utils.create-token-values(tokens-mat-legacy-button-toggle.$prefix,
@@ -35,6 +48,7 @@
 
 @mixin theme($theme) {
   @include theming.private-check-duplicate-theme-styles($theme, 'mat-button-toggle') {
+    @include base($theme);
     @if inspection.theme-has($theme, color) {
       @include color($theme);
     }

src/material/button-toggle/button-toggle.scss

@@ -27,11 +27,6 @@ $_standard-tokens: (
 
 .mat-button-toggle-standalone,
 .mat-button-toggle-group {
-  @include token-utils.create-token-values(
-    tokens-mat-legacy-button-toggle.$prefix,
-    tokens-mat-legacy-button-toggle.get-unthemable-tokens()
-  );
-
   @include elevation.overridable-elevation(2);
   position: relative;
   display: inline-flex;
@@ -54,11 +49,6 @@ $_standard-tokens: (
 
 .mat-button-toggle-standalone.mat-button-toggle-appearance-standard,
 .mat-button-toggle-group-appearance-standard {
-  @include token-utils.create-token-values(
-    tokens-mat-standard-button-toggle.$prefix,
-    tokens-mat-standard-button-toggle.get-unthemable-tokens()
-  );
-
   @include token-utils.use-tokens($_standard-tokens...) {
     @include token-utils.create-token-slot(border-radius, shape);
     border: solid 1px var(#{token-utils.get-token-variable(divider-color)});
@@ -122,11 +112,6 @@ $_standard-tokens: (
 }
 
 .mat-button-toggle-appearance-standard {
-  @include token-utils.create-token-values(
-    tokens-mat-standard-button-toggle.$prefix,
-    tokens-mat-standard-button-toggle.get-unthemable-tokens()
-  );
-
   @include token-utils.use-tokens($_standard-tokens...) {
     $divider-color: var(#{token-utils.get-token-variable(divider-color)});
     @include token-utils.create-token-slot(color, text-color);