Add nheko specific account data type for hiding event types

CMakeLists.txt

include/mtx/events.hpp

include/mtx/events/collections.hpp

include/mtx/events/nheko_extensions/hidden_events.hpp

include/mtx/events/tag.hpp

include/mtx/responses/sync.hpp

lib/structs/events.cpp

lib/structs/events/collections.cpp

lib/structs/events/nheko_extensions/hidden_events.cpp

lib/structs/responses/common.cpp

lib/structs/responses/sync.cpp

tests/events.cpp