Add P-Chain ConstructionHash support

[simonzxw777-cb]

What is PR about?

1. Add P-Chain support for Hash function (ConstructionHash) in service_construction.go .
2. Add unit test for P-chain Hash support.
3. Add CChainNetWorkIdentifier to distinguished sub chain.

How did it test?

1. Firstly, using platform.getTx api to get a random transaction that exists in the testnet. Here is example:

$ curl -X POST --data '{ 0s
"jsonrpc": "2.0",
"method": "platform.getTx",
"params": {
"txID":"etWqwTN1YwhakxLnMDp7q6yaf4m7VJu4uB4vC4fEtNrFe9sDy",
"encoding": "hex"
},
"id": 1
}' -H 'content-type:application/json;' XXXXXXXX/ext/bc/P

Return:

{"jsonrpc":"2.0","result":{"tx":"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","encoding":"hex"},"id":1}

2. We want to transfer tx in the return result to txID in the call command. Writing unit test to verify it.
3. Note that we still need to make sure the format of input transaction.