Add support for m.direct

CMakeLists.txt

include/mtx/events/account_data/direct.hpp

include/mtx/events/collections.hpp

include/mtx/events/event_type.hpp

include/mtxclient/http/client.hpp

lib/http/client.cpp

lib/structs/events.cpp

lib/structs/events/account_data/direct.cpp

lib/structs/events/collections.cpp

lib/structs/responses/common.cpp

tests/events.cpp