Fix NPE when a workflow implementation uses a composed @WorkflowImpl annotation

[muhrifqii]

What was changed

WorkersTemplate#configureWorkflowImplementationsByWorkerName now uses AnnotationUtils.findAnnotation instead of Class#getAnnotation to look up @WorkflowImpl.
Added AutoDiscoveryComposedAnnotationTest and a dedicated composedannotation fixture package that reproduce the bug with a user-defined composed annotation on both a workflow and an activity implementation.

Why?

If a workflow implementation class is annotated with a custom composed (meta) annotation, for example a user-defined annotation that is itself annotated with @WorkflowImpl, rather than @WorkflowImpl applied directly - worker auto-discovery threw an NPE.
Class#getAnnotation only resolves annotations present directly on the class, so it returned null, and the next line (annotation.workers()) NPE'd.

@ActivityImpl/@NexusServiceImpl lookups were already consistent throughout, which is why only workflows registered via workers() were affected.

Checklist

1. Closes N/A - found while implementing temporal-spring-boot-autoconfigure in an application with a custom composed annotation.

2. How was this tested:
   Added AutoDiscoveryComposedAnnotationTest, confirmed it reproduces the NPE before the fix and passes after
   Ran the full temporal-spring-boot-autoconfigure test suite; all tests pass.

3. Any docs updates needed?
   No.

[CLAassistant]

All committers have signed the CLA.

[maciejdudko]

Hi @muhrifqii, thank you for your contribution and for reporting the problem. I have reviewed the PR and I think it's good, it just needs one correction to tests before we can merge it (see comment).

[maciejdudko]

Timeout needs to be longer so that it works reliably in CI environment.

Suggested change

	.setStartToCloseTimeout(Duration.ofSeconds(1))
	.setStartToCloseTimeout(Duration.ofSeconds(10))