Argent account implementation

[dribeiro-ShardLabs]

Usage related changes

• Argent Account implementation can now be used:
  • additional functionalities for guardian setting await loadedAccount.setGuardian(account.guardianPrivateKey) ;
  • can be deployed and used the same way as the OpenZeppelin implementation, e.g account = await starknet.deployAccount("ArgentAccount"), but to load from an address or to change the guardian, must import import { ArgentAccount } from "@shardlabs/starknet-hardhat-plugin/dist/account" and cast as ArgentAccount const loadedAccount = (await starknet.getAccountFromAddress(accountAddress, privateKey, "ArgentAccount")) as ArgentAccount
• Both Argent and OZ implementations now support multicall/invoke, described in README

Development related changes

• Implemented Argent Account, changed way OZ implementation invokes, now it uses multicall/invoke, without breaking changes

Checklist:

• I have formatted the code
• I have performed a self-review of the code
• I have rebased to the base branch
• I have documented the changes
• I have updated the tests
• I have created a PR to the plugin branch of starknet-hardhat-example.

[FabijanC]

Similar to config.yml, I see formatting has been applied. I've been avoiding that change as it makes the review difficult. If you could revert the formatting changes, then I'd be able to review more easily.