migrate to std::filesystem

src/archiver.cpp

src/data_transfer.cpp

src/fileutils.cpp

src/fileutils.h

src/jamidht/account_manager.cpp

src/jamidht/conversation.cpp

src/jamidht/conversation_module.cpp

src/jamidht/conversation_module.h

src/jamidht/conversationrepository.cpp

src/jamidht/gitserver.cpp

src/jamidht/jamiaccount.cpp

src/jamidht/namedirectory.cpp

src/jamidht/transfer_channel_handler.cpp

src/jamidht/transfer_channel_handler.h

src/manager.cpp

src/media/media_encoder.cpp

src/media/recordable.cpp

src/plugin/jamipluginmanager.cpp

src/plugin/jamipluginmanager.h

src/plugin/pluginpreferencesutils.cpp