Speed up compilation a bit

CMakeLists.txt

im.nheko.Nheko.yaml

src/AliasEditModel.cpp

src/AliasEditModel.h

src/AvatarProvider.cpp

src/AvatarProvider.h

src/BlurhashProvider.cpp

src/Cache.cpp

src/Cache_p.h

src/ChatPage.cpp

src/CompletionProxyModel.cpp

src/EventAccessors.cpp

src/InviteesModel.cpp

src/JdenticonProvider.cpp

src/JdenticonProvider.h

src/Logging.cpp

src/Logging.h

src/LoginPage.cpp

src/MainWindow.h

src/MatrixClient.cpp