RPC: Allow RPC methods accepting options to take named parameters

Co-authored-by: Andrew Chow <github@achow101.com>

doc/release-notes-26485.md

@@ -0,0 +1,16 @@
+JSON-RPC
+---
+
+For RPC methods which accept `options` parameters ((`importmulti`, `listunspent`, `fundrawtransaction`, `bumpfee`, `send`, `sendall`, `walletcreatefundedpsbt`, `simulaterawtransaction`), it is now possible to pass the options as named parameters without the need for a nested object. (#26485)
+
+This means it is possible make calls like:
+
+```sh
+src/bitcoin-cli -named bumpfee txid fee_rate=100
+```
+
+instead of
+
+```sh
+src/bitcoin-cli -named bumpfee txid options='{"fee_rate": 100}'
+```