ERC-20 Support

This PR adds initial support for ERC-20 construction. This means it is now possible to use avalanche-rosetta for E2E ERC-20 support on the C-Chain.

What's Changed

• [CPT-142] Construction api by @learyce in #63
• use coreth's codec by @dhrubabasu in #71
• harden allowed config parameters by @learyce in #75
• release testing by @patrick-ogrady in #74
• cleanup client package by @dhrubabasu in #66
• fix urls by @dhrubabasu in #76

Full Changelog: v0.0.29...v0.1.0