util: move fees.h and error.h to common/messages.h

Move enum and message formatting functions to a common/messages header where
they should be more discoverable, and also out of the util library, so they
will not be a dependency of the kernel

The are no changes in behavior and no changes to the moved code.

src/wallet/spend.cpp

@@ -4,6 +4,7 @@
 
 #include <algorithm>
 #include <common/args.h>
+#include <common/messages.h>
 #include <common/system.h>
 #include <consensus/amount.h>
 #include <consensus/validation.h>
@@ -15,7 +16,6 @@
 #include <script/signingprovider.h>
 #include <script/solver.h>
 #include <util/check.h>
-#include <util/fees.h>
 #include <util/moneystr.h>
 #include <util/rbf.h>
 #include <util/trace.h>
@@ -29,6 +29,8 @@
 
 #include <cmath>
 
+using common::StringForFeeReason;
+using common::TransactionErrorString;
 using interfaces::FoundBlock;
 
 namespace wallet {