Inspection/Evasion tasks roadmap

[Mark2000]

These are a very popular class of RL problems for spacecraft tasking. What would we need to do to enable this type of research?

[Mark2000]

[ ] Per #201, there should be an option to add non-agent satellites to the environment. They should just execute some default FSW mode and not be included in reward/observations/actions/etc.
[ ] Thruster dynamics model.
[ ] FSW for controlling thrusters via absolute thrusts, relative OE control, etc.
[ ] Action for setting thrusters + duration
[ ] Observations that are relative to passive satellite (how to link sats?)
[ ] Reward model for agent observation amount, penalty model for use of thrust (Requires #105 to use both)