Add SysID targeting to mount options dropdown

[timtuxworth]

Issue details

There is now an option for SysID targeting in Mount options, but Mission Planner doesn't yet have an option to select it. Here's the discuss post from @rmackay9

Version

4.5.1 (master)

Platform

[ X] All [ ] AntennaTracker [ ] Copter [ ] Plane [ ] Rover [ ] Sub

Airframe type

Copter, Plane

Hardware type

Cube Red, Zealot H743

Logs

May be able to add later

[rmackay9]

Thanks very much. The full list of mount modes is here https://mavlink.io/en/messages/common.html#MAV_MOUNT_MODE

So we are missing two from the drop-down:

• MAV_MOUNT_MODE_SYSID_TARGET
• MAV_MOUNT_MODE_HOME_TARGET