fix(multiple): fix disabled label style (#25181)

MDC does not set the disabled text color on the label for the checkbox,
radio, or switch. This change applies it on the Angular Material side.

Author: mmalerba

src/material-experimental/mdc-checkbox/_checkbox-theme.scss

@@ -32,6 +32,7 @@
   $primary: mat.get-color-from-palette(map.get($config, primary));
   $accent: mat.get-color-from-palette(map.get($config, accent));
   $warn: mat.get-color-from-palette(map.get($config, warn));
+  $foreground: map.get($config, foreground);
 
   @include mat.private-using-mdc-theme($config) {
     .mat-mdc-checkbox {
@@ -64,6 +65,11 @@
         @include _selected-ripple-colors($warn, error);
       }
     }
+
+    .mat-mdc-checkbox-disabled label {
+      // MDC should set the disabled color on the label, but doesn't, so we do it here instead.
+      color: mat.get-color-from-palette($foreground, disabled-text);
+    }
   }
 }
 

src/material-experimental/mdc-radio/_radio-theme.scss

@@ -21,6 +21,7 @@
   $primary: mat.get-color-from-palette(map.get($config, primary));
   $accent: mat.get-color-from-palette(map.get($config, accent));
   $warn: mat.get-color-from-palette(map.get($config, warn));
+  $foreground: map.get($config, foreground);
 
   @include mat.private-using-mdc-theme($config) {
     $on-surface: rgba(mdc-theme-color.$on-surface, 0.54);
@@ -46,6 +47,11 @@
 
       --mat-mdc-radio-ripple-color: #{mdc-theme-color.prop-value(on-surface)};
 
+      // MDC should set the disabled color on the label, but doesn't, so we do it here instead.
+      .mdc-radio--disabled + label {
+        color: mat.get-color-from-palette($foreground, disabled-text);
+      }
+
       &.mat-primary {
         @include _color-palette($primary);
       }

src/material-experimental/mdc-slide-toggle/_slide-toggle-theme.scss

@@ -73,6 +73,7 @@
   $accent: mat.get-color-from-palette(map.get($config, accent));
   $warn: mat.get-color-from-palette(map.get($config, warn));
   $is-dark: map.get($config, is-dark);
+  $foreground: map.get($config, foreground);
 
   @include mat.private-using-mdc-theme($config) {
     // MDC's switch doesn't support a `color` property. We add support
@@ -81,6 +82,11 @@
       @include mdc-form-field.core-styles($query: mat.$private-mdc-theme-styles-query);
       @include mdc-switch-theme.theme(_get-theme-base-map($is-dark));
 
+      // MDC should set the disabled color on the label, but doesn't, so we do it here instead.
+      .mdc-switch--disabled + label {
+        color: mat.get-color-from-palette($foreground, disabled-text);
+      }
+
       &.mat-primary {
         @include mdc-switch-theme.theme(_get-theme-color-map($primary));
       }