Merge #14565: Overhaul importmulti logic

eacff95 Add release notes (Pieter Wuille)
bdacbda Overhaul importmulti logic (Pieter Wuille)

Pull request description:

  This is an alternative to #14558 (it will warn when fields are being ignored). In addition:
  * It makes sure no changes to the wallet are made when an error in the input exists.
  * It validates all arguments, and will fail if anything fails to parse.
  * Adds a whole bunch of sanity checks

Tree-SHA512: fdee0b6aca8c643663f0bc295a7c1d69c1960951493b06abf32c58977f3e565f75918dbd0402dde36e508dc746c9310a968a0ebbacccc385a57ac2a68b49c1d0

Author: meshcollider

doc/release-notes-14565.md

@@ -0,0 +1,5 @@
+Low-level RPC changes
+---------------------
+
+The `importmulti` RPC will now contain a new per-request `warnings` field with strings
+that explain when fields are being ignored or inconsistant, if any.