Add voice call management

README.md

qmi/src/lib.rs

qmi/src/struct.rs

qmi/src/tests.rs

wroomd/src/context.rs

wroomd/src/dbus.rs

wroomd/src/devices/mod.rs

wroomd/src/devices/qmi_common/mod.rs

wroomd/src/devices/qmi_common/voice.rs

wroomd/src/devices/qmi_modem.rs

wroomd/src/event.rs

wroomd/src/state.rs