Add partially signed transaction from rnicoll

[rnicoll]

Generated with:

dogecoin-cli walletprocesspsbt `cat 1_transaction.psbt`

[patricklodder]

This now works and analyzepsbt got out of the next: updateutxo loop it was in for me:

{
  "inputs": [
    {
      "has_utxo": true,
      "is_final": false,
      "next": "signer",
      "missing": {
        "signatures": [
          "126da80222834eea3f8e724608080dde2893aff2",
          "016fd925f47ef94eec9b598d5622156a51ee76e9",
          "dde6b6088bd74d70e3b3e4d1418e73138505eb87",
          "5b94ca94a383d95f509e4e43906d4c0fcbd5482a"
        ]
      }
    }
  ],
  "estimated_vsize": 1191,
  "estimated_feerate": 4.19815281,
  "fee": 5.00000000,
  "next": "signer"
}

Also after the second commit the psbt actually contains the signature.