Add simple API for making Transfer deploys enhancement proposal

[Volodymyr-Kuchinskyi]

It would be a very good extension for the existing functionality to have a method that creates a transfer deploy from basic parameters:

type TransferDeployParams struct {
  Account       keypair.PublicKey
  Sender         keypair.PublicKey
  Recipient     keypair.PublicKey
  Amount.       uint64
  ChainName string
}
func MakeTransferDeploy(params TransferDeployParams) types.Deploy

Example of a use case:

deploy := casper.MakeTransferDeploy(casper.TransferDeployParams{
  Account:       key.PublicKey(),
  Sender:         key.PublicKey(),
  Recipient:     recipientPublicKey,
  Amount:       10000,
  ChainName: "casper-test",
})
deploy.SignDeploy(key)
casperClient.PutDeploy(deploy)