test: add test categorization for better test organization

- Add IntegrationTest and UnitTest marker interfaces
- Enable selective test execution based on categories
- Support for categorized test runs in CI/CD pipelines

Author: bsbodden

core/src/test/java/com/redis/vl/test/categories/IntegrationTest.java

@@ -0,0 +1,7 @@
+package com.redis.vl.test.categories;
+
+/**
+ * Marker interface for integration tests that require external resources. These tests typically
+ * need Redis, download models, or make API calls.
+ */
+public interface IntegrationTest {}

core/src/test/java/com/redis/vl/test/categories/SlowTest.java

@@ -0,0 +1,7 @@
+package com.redis.vl.test.categories;
+
+/**
+ * Marker interface for slow tests that should be excluded from regular builds. These tests
+ * typically involve network calls, large file downloads, or long-running operations.
+ */
+public interface SlowTest {}