feat: refactor VerifyLeafHashes, VerifyNamespace, and VerifyInclusion to expose computing root and validations outside of Proof (#291)

Fixes #290 

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

- **New Features**
- Enhanced data integrity verification with a refined cryptographic
proof process and improved error handling.
- **Refactor**
- Streamlined the underlying verification flow to simplify the
validation logic and bolster system reliability.
- Isolated root computation logic into a dedicated method for improved
modularity.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: gupadhyaya