Test network upgrade logic

Also demonstrates how to specify a network upgrade.

src/consensus/params.h

@@ -21,6 +21,7 @@ namespace Consensus {
 enum UpgradeIndex {
     // Sprout must be first
     BASE_SPROUT,
+    UPGRADE_TESTDUMMY,
     // NOTE: Also add new upgrades to NetworkUpgradeInfo in upgrades.cpp
     MAX_NETWORK_UPGRADES
 };