refactor: Move fs.* to util/fs.*

The fs.* files are already part of the libbitcoin_util library. With the
introduction of the fs_helpers.* it makes sense to move fs.* into the
util/ directory as well.

src/init.cpp

@@ -20,7 +20,6 @@
 #include <chainparams.h>
 #include <consensus/amount.h>
 #include <deploymentstatus.h>
-#include <fs.h>
 #include <hash.h>
 #include <httprpc.h>
 #include <httpserver.h>
@@ -70,6 +69,7 @@
 #include <txmempool.h>
 #include <util/asmap.h>
 #include <util/check.h>
+#include <util/fs.h>
 #include <util/fs_helpers.h>
 #include <util/moneystr.h>
 #include <util/strencodings.h>