feat(commander): add setpoint types

Switches from using VehicleControlMode to a specific setpoint type message
with reply.
Reasons:
- in case a VehicleControlMode was dropped (e.g. when the mode switched
  setpoint type), no confirmation was returned, and resulting in wrong
  controller flags.
- cleaner interface separation: external modes do not need to configure
  (or know) which controller to run for a certain setpoint
- allows for external modes to check for compatibility: e.g. a mode using
  fixed-wing setpoint types can now be rejected on a multicopter.
- allows for further extensions, like a setpoint timeout

This makes it a bit more effort to add a new setpoint type. Specifically,
setpoint_types.cpp needs to be extended when adding a new setpoint message.

PX4 internal modes also make use of the setpoint types. The information
flow is:
nav_state -> setpoint type -> vehicle control mode flags

It also adds a timeout to the setpoint config, but is not implemented
yet.

This changes the interface for external modes and thus the compatibility
version is increased.

msg/versioned/SetpointConfigReply.msg

@@ -0,0 +1,22 @@
+# Reply to SetpointConfig
+
+uint32 MESSAGE_VERSION = 0
+
+uint64 timestamp # [us] Time since system start
+
+uint16 type # See SetpointConfig::TYPE_*
+
+uint8 source_id # nav_state of the mode that sent the SetpointConfig
+
+uint8 RESULT_SUCCESS = 0
+uint8 RESULT_FAILURE_OTHER = 1
+uint8 RESULT_UNSUPPORTED = 2 # Setpoint type is unsupported for the current vehicle
+uint8 RESULT_UNKNOWN_SETPOINT_TYPE = 3 # The setpoint type is not known
+uint8 result # [@enum RESULT]
+
+# Mode requirements for using the given setpoint type. A mode will use these and apply them to the arming check reply (PX4 does not do that itself).
+# Certain setpoint types can be used in a reduced way, for example a TrajectorySetpoint without position control. In that case PX4 still sets all requirement flags, and the mode will then ignore mode_req_local_position.
+bool mode_req_angular_velocity
+bool mode_req_attitude
+bool mode_req_local_alt
+bool mode_req_local_position