Add bscscan for Etherscan Providers

[mcastiglione777]

Hello, please add bscscan (Binance Chain Etherscan) for Etherscan providers
the base URL is https://api.bscscan.com/

I use ethers.js and I need to use this endpoint so I can add historical data support for Binance Smart Chain.

the file is this one:
packages/providers/src.ts/etherscan-provider.ts

Right now the options are these:
switch(name) {
case "homestead":
baseUrl = "https://api.etherscan.io";
break;
case "ropsten":
baseUrl = "https://api-ropsten.etherscan.io";
break;
case "rinkeby":
baseUrl = "https://api-rinkeby.etherscan.io";
break;
case "kovan":
baseUrl = "https://api-kovan.etherscan.io";
break;
case "goerli":
baseUrl = "https://api-goerli.etherscan.io";
break;
default:
throw new Error("unsupported network");
}

It should be like this:

    switch(name) {
        case "homestead":
            baseUrl = "https://api.etherscan.io";
            break;
        case "ropsten":
            baseUrl = "https://api-ropsten.etherscan.io";
            break;
        case "rinkeby":
            baseUrl = "https://api-rinkeby.etherscan.io";
            break;
        case "kovan":
            baseUrl = "https://api-kovan.etherscan.io";
            break;
        case "goerli":
            baseUrl = "https://api-goerli.etherscan.io";
            break;
        case "smartchain":
            baseUrl = "https://api.bscscan.com";
            break;
        default:
            throw new Error("unsupported network");
    }

Also, there should be a handler for getEtherPrice, like this:
delete these two lines:
if (this.network.name !== "homestead") { return 0.0; }
url += "?module=stats&action=ethprice";
add:
if (this.network.name !== "homestead" && this.network.name !== "smartchain") { return 0.0; }
if (this.network.name == "smartchain") {
url += "?module=stats&action=bnbprice";
} else {
url += "?module=stats&action=ethprice";
}

Thank you very much
Marco

[ricmoo]

Closing this in favour of #1204.

Please comment there, and include any additional information.

Thanks! :)