"gqls" files are not supported

This creates an awkward situation where Spring for GraphQL users are instructed to use DGS codegen (or do it out of their own accord) and notice that their .gqls files are not being picked up. https://docs.spring.io/spring-boot/3.4/appendix/application-properties/index.html#application-properties.web.spring.graphql.schema.file-extensions