refactor(feature-store): Rewrite FeatureGroupManager from inheritance to composition

Replace FeatureGroup inheritance with composition pattern. The manager
now delegates to FeatureGroup via classmethods (create_feature_group,
describe_feature_group) and takes a FeatureGroup instance in
enable_lake_formation instead of operating on self.

Key changes:
- FeatureGroupManager no longer extends FeatureGroup
- Forward session/region through enable_lake_formation and create
- Add telemetry decorators to all public methods
- Add hypothesis to test dependencies
- Add dedicated test_feature_group_manager.py unit tests
- Consolidate test_lakeformation.py (remove migrated tests)
- Update integration tests for new API surface
- Reorganize example notebooks into v3-feature-store-examples/
- Bump VERSION to 1.5.1.dev0
---
X-AI-Prompt: read last commit and update commit message to reflect full scope of changes
X-AI-Tool: kiro-cli

Author: BassemHalim

requirements/extras/test_requirements.txt

@@ -1,6 +1,7 @@
 pytest
 pytest-cov
 pytest-xdist
+hypothesis
 mock
 pydantic==2.11.9
 pydantic_core==2.33.2