Merge bitcoin/bitcoin#25013: Remove cs_main from verifymessage, move msg utils to new file

fa60169811 rpc: Move signmessage RPC util to new file (MacroFake)
fa9425177e Remove cs_main from verifymessage (MacroFake)

Pull request description:

  The `verifymessage` RPC has several issues:

  * It takes `cs_main` for no reason, blocking progress on removing the `cs_main` global mutex.
  * It is located in a file called `misc`, which is not a very helpful name.

  Fix all issues.

ACKs for top commit:
  vincenzopalazzo:
    ACK https://github.com/bitcoin/bitcoin/pull/25013/commits/fa60169811d6991a116bd37e1ff58049d2beee77

Tree-SHA512: c71a1f481b828e0a544405fecbbc7ca44e66ea46b498d7aed1f1c584d6a99724deb13e89d90b9d5cdeecbce293e6a41e9f7ae299543f6d761bf9e7a839b6c7f3

ci/test/06_script_b.sh

@@ -38,7 +38,11 @@ if [ "${RUN_TIDY}" = "true" ]; then
   export P_CI_DIR="${BASE_BUILD_DIR}/bitcoin-$HOST/src/"
   CI_EXEC run-clang-tidy "${MAKEJOBS}"
   export P_CI_DIR="${BASE_BUILD_DIR}/bitcoin-$HOST/"
-  CI_EXEC "python3 ${BASE_SCRATCH_DIR}/iwyu/include-what-you-use/iwyu_tool.py src/compat src/init -p . ${MAKEJOBS} -- -Xiwyu --cxx17ns -Xiwyu --mapping_file=${BASE_BUILD_DIR}/bitcoin-$HOST/contrib/devtools/iwyu/bitcoin.core.imp"
+  CI_EXEC "python3 ${BASE_SCRATCH_DIR}/iwyu/include-what-you-use/iwyu_tool.py"\
+          " src/compat"\
+          " src/init"\
+          " src/rpc/signmessage.cpp"\
+          " -p . ${MAKEJOBS} -- -Xiwyu --cxx17ns -Xiwyu --mapping_file=${BASE_BUILD_DIR}/bitcoin-$HOST/contrib/devtools/iwyu/bitcoin.core.imp"
 fi
 
 if [ "$RUN_SECURITY_TESTS" = "true" ]; then