kernel: Add progress method to notifications

This commit is part of the libbitcoinkernel project and seeks to remove
the ChainstateManager's and, more generally, the kernel library's
dependency on interface_ui with options methods in this and the
following few commits. By removing interface_ui from the kernel library,
its dependency on boost is reduced to just boost::multi_index.

src/node/chainstate.cpp

@@ -253,7 +253,7 @@ ChainstateLoadResult VerifyLoadedChainstate(ChainstateManager& chainman, const C
                                                          "Only rebuild the block database if you are sure that your computer's date and time are correct")};
             }
 
-            VerifyDBResult result = CVerifyDB().VerifyDB(
+            VerifyDBResult result = CVerifyDB(chainman.GetNotifications()).VerifyDB(
                 *chainstate, chainman.GetConsensus(), chainstate->CoinsDB(),
                 options.check_level,
                 options.check_blocks);