static Function<String, Optional<ProjectionTransformer>> createServiceFactory() {
        return createServiceFactory(ServiceLoader.load(ProjectionTransformer.class));
    }
Creates a {@code ProjectionTransformer} factory function using SPI
and the current thread's context class loader.

@return Returns the created factory function.
@see Thread#getContextClassLoader()
smithy-build/src/main/java/software/amazon/smithy/build/ProjectionTransformer.java