Add Celo and Alfajores in networks available to verify contracts via `hardhat verify`

[therealharpaljadeja]

Description of the issue

At CELO, we are looking to easily + automatically verify contracts on the Celo and Alfajores network.

Verifying contracts via the RPC endpoint of the Celo Blockscout instance is quite complicated. We currently rely on manual verification by flattening Solidity files.

It would be great if we could add the Celo and Alfajores network to the list of networks available on the hardhat-etherscan package.

This would help us (the team) tremendously and would provide a better developer experience for people building on Celo. Verifying contracts on Celo and Alfajores from any hardhat project would be as simple as running the command

npx hardhat verify --network celo

It would then be more developer/user friendly to interact with them via the Celoscan explorer using the contract methods fields.

Proposed solution

Add the Celo and Alfajores network to the list of networks under the @nomiclabs/hardhat-etherscan package.

#2933

[github-actions[bot]]

This issue is also being tracked on Linear.

We use Linear to manage our development process, but we keep the conversations on Github.

LINEAR-ID: 81e5045f-863b-4e48-a9af-82aac8991a0e

[joenyzio]

I'd love to see this. Super helpful!

[ericnakagawa]

Would love to see this PR accepted. It is the top feature request from the many hackathons we have supported this year.

Improving the verification process for Celo devs helps increase quality and security of our community!

[viral-sangani]

This would make verification on Celo seamless. Can't wait to see this PR merged. 🤩

[fvictorio]

Closing this since in general we are not adding new networks to hardhat-verify.

Adding support for a new network is simple, check here. This can then be easily packaged in a hardhat-celo plugin. Happy to answer questions/light review that if someone implements it.