wallet: Add wallet/types.h for simple public enum and struct types

Move isminetype and isminefilter there this commit, add WalletPurpose type next
commit.

src/wallet/test/ismine_tests.cpp

@@ -8,7 +8,7 @@
 #include <script/script.h>
 #include <script/standard.h>
 #include <test/util/setup_common.h>
-#include <wallet/ismine.h>
+#include <wallet/types.h>
 #include <wallet/wallet.h>
 
 #include <boost/test/unit_test.hpp>