Add ChainstateManager::m_adjusted_time_callback

This decouples validation.cpp from netaddress.cpp (transitively,
timedata.cpp, and asmap.cpp).

This is important for libbitcoinkernel as:

- There is no reason for the consensus engine to be coupled with
  netaddress, timedata, and asmap
- Users of libbitcoinkernel can now easily supply their own
  std::function that provides the adjusted time.

See the src/Makefile.am changes for some satisfying removals.

src/test/validation_chainstate_tests.cpp

@@ -3,13 +3,14 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 //
 #include <chainparams.h>
-#include <random.h>
-#include <uint256.h>
 #include <consensus/validation.h>
-#include <sync.h>
+#include <random.h>
 #include <rpc/blockchain.h>
+#include <sync.h>
 #include <test/util/chainstate.h>
 #include <test/util/setup_common.h>
+#include <timedata.h>
+#include <uint256.h>
 #include <validation.h>
 
 #include <vector>
@@ -24,6 +25,7 @@ BOOST_AUTO_TEST_CASE(validation_chainstate_resize_caches)
 {
     const ChainstateManager::Options chainman_opts{
         Params(),
+        GetAdjustedTime,
     };
     ChainstateManager manager{chainman_opts};