Consensus: Policy: MOVEONLY: Move CFeeRate out of the consensus module

...from amount.o to policy/feerate.o

Policy, because it moves policy code to the policy directory (common module)

src/test/amount_tests.cpp

@@ -3,6 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "amount.h"
+#include "policy/feerate.h"
 #include "test/test_bitcoin.h"
 
 #include <boost/test/unit_test.hpp>