Make Chain's to_string and from_str inverse functions

[meetmangukiya]

Is your feature request related to a problem? Please describe.
Currently, to_string and from_str are not mirroring each other, maybe they should.

Describe the solution you'd like
Make to_string and from_str inverse functions

let chain_name = "mainnet";

let chain = Chain::from_str(chain_name)?;
assert_eq!(chain.to_string(), chain_name);

[mattsse]

this is done in the display impl

ethers-rs/ethers-core/src/types/chain.rs

Lines 41 to 45 in b07b302

	impl fmt::Display for Chain {
	fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
	write!(formatter, "{:?}", self)
	}
	}

which by default prints the Variant name,
simply inversing the FromStr match would be better

Do you want to take this on? Basically switching left and right arm of this match

ethers-rs/ethers-core/src/types/chain.rs

Lines 98 to 120 in b07b302

	Ok(match chain {
	"mainnet" => Chain::Mainnet,
	"ropsten" => Chain::Ropsten,
	"rinkeby" => Chain::Rinkeby,
	"goerli" => Chain::Goerli,
	"kovan" => Chain::Kovan,
	"xdai" => Chain::XDai,
	"polygon" => Chain::Polygon,
	"polygon-mumbai" => Chain::PolygonMumbai,
	"avalanche" => Chain::Avalanche,
	"avalanche-fuji" => Chain::AvalancheFuji,
	"sepolia" => Chain::Sepolia,
	"moonbeam" => Chain::Moonbeam,
	"moonbeam-dev" => Chain::MoonbeamDev,
	"moonriver" => Chain::Moonriver,
	"optimism" => Chain::Optimism,
	"optimism-kovan" => Chain::OptimismKovan,
	"fantom" => Chain::Fantom,
	"fantom-testnet" => Chain::FantomTestnet,
	"bsc" => Chain::BinanceSmartChain,
	"bsc-testnet" => Chain::BinanceSmartChainTestnet,
	"arbitrum" => Chain::Arbitrum,
	"arbitrum-testnet" => Chain::ArbitrumTestnet,