chore: add KIND_CONFIG variable to override kind configuration (#19)

## What
<!-- One sentence summary -->
Allows overriding kind cluster, required for OIDC setup for kind cluster
used by UI E2E test, see
opendefensecloud/solution-arsenal#397

## Why
<!-- Motivation / problem being solved. Skip if obvious from the linked
issue. -->
See above.

## Testing
<!-- How was this tested? e.g. unit, envtest, manual against vX.Y.Z -->
See above.

## Checklist
- [x] Tests added/updated
- [x] No breaking changes (or upgrade path documented above)
- [x] Readable commit history (squashed and cleaned up as desired)
- [x] AI code review considered and comments resolved


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

## Release Notes

* **Chores**
* Enhanced local cluster setup to support custom Kind cluster
configuration when specified.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: trevex

common.mk

@@ -200,7 +200,7 @@ setup-local-cluster: ## Set up a Kind cluster for local development if it does n
 			echo "Kind cluster '$(KIND_CLUSTER)' already exists. Skipping creation." ;; \
 		*) \
 			echo "Creating Kind cluster '$(KIND_CLUSTER)'..."; \
-			$(KIND) create cluster --name $(KIND_CLUSTER) ;; \
+			$(KIND) create cluster --name $(KIND_CLUSTER) $(if $(KIND_CONFIG),--config $(KIND_CONFIG)) ;; \
 	esac
 
 ##@ Common golang targets