Fix for URL used with Cloudflare issuance

Compatibility fixes for hCaptcha redemption

Some minor compatibility fixes for HC config

- Fixed verification of DLEQ proofs.
- Build using yarn.
- Using Jest testing framework for unit/integration tests.
Elliptic curve optimizations.
- Implementation of simplified SWU compliant with draft-irtf-cfrg-hash-to-curve-03.
- allow client to specify which has-to-curve algorithm to use.
- allow client to use compressed or uncompressed representations when encoding points.
- Configuration of workflow using central configuration file (src/ext/config.js).
- Allows us to specify new workflows for different providers (see hCaptcha).
VOPRF key commitments have been moved to external repo.
- Allows key rotation to be performed separately from extension update.
- Commitments contain signature which is verified and expiry date.
- Fixed some minor issues when redirecting in Chrome.
- Update popup window
- Allow valid redemption tokens to be logged to console
- Indicate version in HTML