Add an optional outputs_validator parameter to send_transaction rpc

[quake]

Proposal

Outputs validator prevents improperly formed transactions from entering the tx-pool, in most cases the leading cause of client sending these transactions is simply because of bug code or misusing SDK, which results in a none-unlockable transaction.

RPC parameter changes

outputs_validator: Validate the transaction outputs before entering the tx-pool, an optional string parameter, null means using default validator.

Implementation details

CKB will provide two built-in validators, default and passthrough.

For default validator, these checks should conform to the pseudocode described below

transaction.outputs.all{ |output|
    script = output.script
    (script.code_hash == secp256k1_blake160_sighash_all && script.hash_type == "type" && script.args.size == 20) ||
    (script.code_hash == secp256k1_blake160_multisig_all && script.hash_type == "type" && （script.args.size == 20 || (script.args.size == 28 && script.args[20..28].is_valid_since_format))
}
transaction.outputs.all{ |output|
    script = output.type
    script.is_null || script.code_hash == dao && script.hash_type == "type"
}

For passthrough validator, it will skip validation.