Merge bitcoin/bitcoin#30708: rpc: add getdescriptoractivity

37a5c5d836 doc: update descriptors.md for getdescriptoractivity (James O'Beirne)
ee3ce6a4f4 test: rpc: add no address case for getdescriptoractivity (James O'Beirne)
811f76f3a5 rpc: add getdescriptoractivity (James O'Beirne)
25fe087de5 rpc: move-only: move ScriptPubKeyDoc to utils (James O'Beirne)

Pull request description:

  The RPC command `scanblocks` provides a useful way to get a set of blockhashes that have activity relevant to a set of descriptors (`relevant_blocks`). However actually extracting the activity from those blocks is left as an exercise to the end user.

  This process involves not only generating the (potentially ranged) set of scripts for the descriptor set on the client side (maybe via `deriveaddresses`), but then the user must retrieve each block's contents one-by-one using `getblock <hash>`, which is transmitted over a network link. And that's all before they perform the actual search over block content. There's even more work required to incorporate unconfirmed transactions.

  This PR introduces an RPC `getdescriptoractivity` that [dovetails](https://bitcoin-irc.chaincode.com/bitcoin-core-dev/2024-08-16#1046393;) with `scanblocks` output, handling the process described above. Users specify the blockhashes (perhaps from `relevant_blocks`) and a set of descriptors; they are then given all spend/receive activity in that set of blocks.

  This is a very useful tool when implementing lightweight wallets that want neither to require a third-party indexer like electrs, nor the overhead of creating and managing watch-only wallets in Core. This allows Core to be more easily used in a "stateless" manner by wallets, with potentially many nodes interchangeably acting as backends.

  ### Example usage

  ```
  % ./src/bitcoin-cli scanblocks start \
      '["addr(bc1p0cp0vyag6snlta2l7c4am3rue7eef9f72l7uhx52m4v27vfydx9s8tfs7t)"]' \
      857263
  {
    "from_height": 857263,
    "to_height": 858263,
    "relevant_blocks": [
      "00000000000000000002bc5cc78f5b0913a5230a8f4b0d5060bc9a60900a5a88",
      "00000000000000000001c5291ed6a40c06d3db5c8fb738567654b24a14b24ecb"
    ],
    "completed": true
  }

  % ./src/bitcoin-cli getdescriptoractivity \
      '["00000000000000000002bc5cc78f5b0913a5230a8f4b0d5060bc9a60900a5a88", "00000000000000000001c5291ed6a40c06d3db5c8fb738567654b24a14b24ecb"]' \
      '["addr(bc1p0cp0vyag6snlta2l7c4am3rue7eef9f72l7uhx52m4v27vfydx9s8tfs7t)"]'
  {
    "activity": [
      {
        "type": "receive",
        "amount": 0.00002900,
        "blockhash": "00000000000000000002bc5cc78f5b0913a5230a8f4b0d5060bc9a60900a5a88",
        "height": 857907,
        "txid": "c9d34f202c1f66d80cae76f305350f5fdde910b97cf6ae6bf79f5bcf2a337d06",
        "vout": 254,
        "output_spk": {
          "asm": "1 7e02f613a8d427f5f55ff62bddc47ccfb394953e57fdcb9a8add58af3124698b",
          "desc": "rawtr(7e02f613a8d427f5f55ff62bddc47ccfb394953e57fdcb9a8add58af3124698b)#yewcd80j",
          "hex": "51207e02f613a8d427f5f55ff62bddc47ccfb394953e57fdcb9a8add58af3124698b",
          "address": "bc1p0cp0vyag6snlta2l7c4am3rue7eef9f72l7uhx52m4v27vfydx9s8tfs7t",
          "type": "witness_v1_taproot"
        }
      },
      {
        "type": "spend",
        "amount": 0.00002900,
        "blockhash": "00000000000000000001c5291ed6a40c06d3db5c8fb738567654b24a14b24ecb",
        "height": 858260,
        "spend_txid": "7f61d1b248d4ee46376f9c6df272f63fbb0c17039381fb23ca5d90473b823c36",
        "spend_vin": 0,
        "prevout_txid": "c9d34f202c1f66d80cae76f305350f5fdde910b97cf6ae6bf79f5bcf2a337d06",
        "prevout_vout": 254,
        "prevout_spk": {
          "asm": "1 7e02f613a8d427f5f55ff62bddc47ccfb394953e57fdcb9a8add58af3124698b",
          "desc": "rawtr(7e02f613a8d427f5f55ff62bddc47ccfb394953e57fdcb9a8add58af3124698b)#yewcd80j",
          "hex": "51207e02f613a8d427f5f55ff62bddc47ccfb394953e57fdcb9a8add58af3124698b",
          "address": "bc1p0cp0vyag6snlta2l7c4am3rue7eef9f72l7uhx52m4v27vfydx9s8tfs7t",
          "type": "witness_v1_taproot"
        }
      }
    ]
  }
  ```

ACKs for top commit:
  instagibbs:
    reACK 37a5c5d836
  achow101:
    ACK 37a5c5d836
  tdb3:
    Code review and light retest ACK 37a5c5d836
  rkrux:
    re-ACK 37a5c5d836

Tree-SHA512: 04aa51e329c6c2ed72464b9886281d5ebd7511a8a8e184ea81249033a4dad535a12829b1010afc2da79b344ea8b5ab8ed47e426d0bf2eb78ab395d20b1da8dbb

test/functional/test_runner.py

@@ -378,6 +378,7 @@ BASE_SCRIPTS = [
     'rpc_deriveaddresses.py --usecli',
     'p2p_ping.py',
     'p2p_tx_privacy.py',
+    'rpc_getdescriptoractivity.py',
     'rpc_scanblocks.py',
     'p2p_sendtxrcncl.py',
     'rpc_scantxoutset.py',