Refactor out translation.h

This is a prerequisite for introducing bilingual error messages.
Note: #includes are arranged by clang-format-diff.py script.

src/util/error.cpp

@@ -4,7 +4,9 @@
 
 #include <util/error.h>
 
+#include <tinyformat.h>
 #include <util/system.h>
+#include <util/translation.h>
 
 std::string TransactionErrorString(const TransactionError err)
 {