fix(material/form-field): move unthemable tokens to theme mixin (#27887)

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)

(cherry picked from commit 3430c4d)

Author: mmalerba

src/material/form-field/_form-field-theme.scss

@@ -12,7 +12,17 @@
 @use './form-field-density';
 
 @mixin base($theme) {
-  // TODO(mmalerba): Move form field base tokens here
+  @include sass-utils.current-selector-or-root() {
+    @include token-utils.create-token-values(
+        tokens-mdc-filled-text-field.$prefix,
+        tokens-mdc-filled-text-field.get-unthemable-tokens());
+    @include token-utils.create-token-values(
+        tokens-mdc-outlined-text-field.$prefix,
+        tokens-mdc-outlined-text-field.get-unthemable-tokens());
+    @include token-utils.create-token-values(
+        tokens-mat-form-field.$prefix,
+        tokens-mat-form-field.get-unthemable-tokens());
+  }
 }
 
 @mixin color($theme) {

src/material/form-field/form-field.scss

@@ -15,7 +15,6 @@
 @use '../core/tokens/m2/mat/form-field' as tokens-mat-form-field;
 @use '../core/tokens/m2/mdc/filled-text-field' as tokens-mdc-filled-text-field;
 @use '../core/tokens/m2/mdc/outlined-text-field' as tokens-mdc-outlined-text-field;
-@use '../core/style/sass-utils';
 @use './form-field-sizing';
 @use './form-field-subscript';
 @use './form-field-focus-overlay';
@@ -44,24 +43,12 @@
 @include mdc-custom-properties.configure(
   $emit-fallback-values: false, $emit-fallback-vars: false) {
 
-  @include sass-utils.current-selector-or-root() {
-    @include token-utils.create-token-values(
-      tokens-mat-form-field.$prefix,
-      tokens-mat-form-field.get-unthemable-tokens());
-  }
-
   .mdc-text-field--filled {
-    @include token-utils.create-token-values(
-      tokens-mdc-filled-text-field.$prefix,
-      tokens-mdc-filled-text-field.get-unthemable-tokens());
     @include mdc-filled-text-field-theme.theme-styles(
       tokens-mdc-filled-text-field.get-token-slots());
   }
 
   .mdc-text-field--outlined {
-    @include token-utils.create-token-values(
-      tokens-mdc-outlined-text-field.$prefix,
-      tokens-mdc-outlined-text-field.get-unthemable-tokens());
     @include mdc-outlined-text-field-theme.theme-styles(
       tokens-mdc-outlined-text-field.get-token-slots());
   }