The RemoveTransaction endpoint removes the transaction with the
provided txid including all its descendants from the internal wallet.
We still keep watching for the address of the transation in case
the transcation is confirmed nonetheless. This command is particular
useful for neutrino backends because new bitcoind versions do not
reply with an invalid transaction error code when the tx published
fails to be included into the mempool (fullnodes do).
As a preparation for the migration to the grpc-gateway/v2 library we
declare each service's REST annotations in its own file. This is
optional in the v1 library but mandatory in v2.
