MOVEONLY: Move key handling code out of wallet to keyman file

Start moving wallet and ismine code to scriptpubkeyman.h, scriptpubkeyman.cpp

The easiest way to review this commit is to run:

   git log -p -n1 --color-moved=dimmed_zebra

And check that everything is a move (other than includes and copyrights comments).

This commit is move-only and doesn't change code or affect behavior.

src/wallet/init.cpp

@@ -10,6 +10,7 @@
 #include <util/moneystr.h>
 #include <util/system.h>
 #include <util/translation.h>
+#include <wallet/scriptpubkeyman.h>
 #include <wallet/wallet.h>
 #include <walletinitinterface.h>