Fix infeasible plan detection

[patmarion]

A common problem is that planning code calls single shot IK to plan an end pose, then plans a posture goal to the end pose. The end pose may be infeasible (info 13) because it violates constraints, but the posture plan is info 1, because it successfully plans to the end pose.

We have some custom code in the valve task which copies the info 13 value from the single shot ik into the info field of the posture plan, but we don't have general support for this.

We could extend the computePostureGoal function so that it can be given an info error code to insert into the plan message is publishes.