feat: added hardhat-abi-exporter plugin to generate ABI-only artifacts on compile

[quiet-node]

Description:

• installed hardhat-abi-exporter plugin
• configured the plugin to automatically generate ABI-only artifacts on compile
• added a new folder contracts-abi which contains the new ABI-only artifacts

Related issue(s):

Partially Fixes #692

Notes for reviewer:

Checklist

• [ ] Documented (Code comments, README, etc.)
• [ ] Tested (unit, integration, etc.)