Use coeurl as the http backend

CMakeLists.txt

examples/crypto_bot.cpp

examples/media_downloader.cpp

examples/online_backup_exporter.cpp

examples/room_feed.cpp

examples/simple_bot.cpp

include/mtxclient/http/asio_overrides.hpp

include/mtxclient/http/client.hpp

include/mtxclient/http/client_impl.hpp

include/mtxclient/http/errors.hpp

include/mtxclient/http/session.hpp

include/mtxclient/utils.hpp

lib/http/client.cpp

lib/http/session.cpp

lib/utils.cpp

tests/client_api.cpp

tests/e2ee.cpp

tests/media_api.cpp