fix(material/schematics): some snack bar styles not being migrated (#26180)

Fixes that a couple of styles were added to the migration mapping.

Fixes #26178.

Author: crisbeto

src/material/schematics/ng-generate/mdc-migration/rules/components/snack-bar/snack-bar-styles.ts

@@ -37,5 +37,7 @@ export class SnackBarMigrator extends StyleMigrator {
     {old: '.mat-snack-bar-container', new: '.mat-mdc-snack-bar-container'},
     {old: '.mat-snack-bar-handset', new: '.mat-mdc-snack-bar-handset'},
     {old: '.mat-simple-snackbar', new: '.mat-mdc-simple-snack-bar'},
+    {old: '.mat-simple-snack-bar-content', new: '.mat-mdc-snack-bar-label'},
+    {old: '.mat-simple-snackbar-action', new: '.mat-mdc-snack-bar-action'},
   ];
 }