[Expeditions] Create common dz abstract class (#1312)

This creates an abstract class in common so zone and world can share
most of the implementation. World now has access to the same dz data and
api as zone.

Rename CharacterChange to AddRemoveCharacter for clarity

Rename GetRemainingDuration to GetDurationRemaining for consistency

Move dynamic zone queries to custom repository methods

common/CMakeLists.txt

@@ -16,6 +16,7 @@ SET(common_sources
 	database_instances.cpp
 	dbcore.cpp
 	deity.cpp
+	dynamic_zone_base.cpp
 	emu_constants.cpp
 	emu_limits.cpp
 	emu_opcodes.cpp
@@ -466,6 +467,7 @@ SET(common_headers
 	database_schema.h
 	dbcore.h
 	deity.h
+	dynamic_zone_base.h
 	emu_constants.h
 	emu_limits.h
 	emu_opcodes.h