Support Sending v2 Transactions

[n8maninger]

The UI currently only supports v1 transactions. It will need to be updated to build and sign v2 transactions after the activation height.

[n8maninger]

@alexfreska assigned to you for now. If the Go SDK needs changes, we can create a sub-issue and assign it to one of the backend devs.

[alexfreska]

@n8maninger do we need support for sending both v1 and v2? Or just migrate the feature to to v2 transactions?

[n8maninger]

We will need to send v1 transactions until the hardfork activates then we can switch to v2

[alexfreska]

ok, so do we want to add both to the UI, and have it dynamically switch to the v2 flow UI once the consensus height reaches activation height?

[n8maninger]

The UX should be transparent to the user. Only the underlying transaction building/signing should change.

if consensus.Index.Height > consensus.Network.HardforkV2.AllowHeight {
  // Instead of `/fund` and `/fund/sf` call `/v2/fund` and `/v2/fund/sf`
  // Use consensus.State.InputSigHash` instead of `WholeTransactionSigHash`
  // Add signatures to V2 transaction type instead of v1
} else {
 // do current stuff
}