Moves the `findBaseClassDeclarations` method into the shared schematic utilities. This method will be useful for future migrations, and for planned changes to the `undecorated-classes-with-decorated-fields` migration. PR Close #35339
Moves the `findBaseClassDeclarations` method into the shared schematic utilities. This method will be useful for future migrations, and for planned changes to the `undecorated-classes-with-decorated-fields` migration. PR Close #35339