Refactor and simplify chain informations

[lumtis]

We currently have information about chains in:
https://github.com/zeta-chain/node-private/blob/develop/common/chain.go
https://github.com/zeta-chain/node-private/blob/develop/common/chains.go

The current way to represent information is IMO a bit messy, we define chain IDs for the different network, then. we define functions to determine if the chain ID is Ethereum, support EVM, is external, is testnet, etc...

It would be clearer I think to add the information in the Chain object itself, and directly retrieve the information from it.

Example of structure:

type Chain struct{
  ChainID int64 // identifier
  ChainName string
  IsExternal bool // external or zetachain
  Network [ZETACHAIN|BITCOIN|ETHEREUM|BSC|...] // the actual network
  NetworkType [PRIVNET|TESTNET|MAINNET]
  VM [NO_VM|EVM|COSMWASM]                                // vm of smart contract platform if any
  Consensus [BITCOIN|ETHEREUM||TENDERMINT] // the underlying consensus, this allow to reuse a specific header/proof system
}