Add tenderly-hardhat verification

[nvitorovic]

• Adds the @tenderly/hardhat-tenderly plugin
• Adds configuration slots
• Extend the README to include instructions

Description

In this PR, Tenderly's hardhat verification support is added to scaffold-eth.

Additional Information

• [x] I have read the contributing docs (if this is your first contribution)
• [x] This is not a duplicate of any existing pull request