Add options support and local variables in handlebarrz

[yesudeep]

Summary

The Python handlebarrz library has pending features for options support and local variables.

Locations

• python/handlebarrz/src/handlebarrz/__init__.py:462: # TODO: options is currently ignored; need to add support for it.
• python/handlebarrz/src/handlebarrz/__init__.py:501: # TODO: get rid of this once the Rust library has a local variables

Acceptance Criteria

• Add options parameter support to helper registration
• Wait for Rust library local variables support
• Remove workaround once Rust support is available