rpc: Push down safe mode checks

This contains most of the changes of 10563 "remove safe mode", but doesn't
remove the safe mode yet, but put an `ObserveSafeMode()` check in
individual calls with okSafeMode=false.

This cleans up the ugly "okSafeMode" flag from the dispatch tables,
which is not a concern for the RPC server.

Extra-author: Wladimir J. van der Laan <laanwj@gmail.com>

src/wallet/rpcdump.cpp

@@ -4,6 +4,7 @@
 
 #include "base58.h"
 #include "chain.h"
+#include "rpc/safemode.h"
 #include "rpc/server.h"
 #include "init.h"
 #include "validation.h"
@@ -174,6 +175,7 @@ UniValue abortrescan(const JSONRPCRequest& request)
             + HelpExampleRpc("abortrescan", "")
         );
 
+    ObserveSafeMode();
     if (!pwallet->IsScanning() || pwallet->IsAbortingRescan()) return false;
     pwallet->AbortRescan();
     return true;