Add Unit Tests for PlanToBasePose() and example code

[DavidB-CMU]

Should SBPL be a required or optional dependency for HERBpy?

The example code uses PlanToBasePose() - how should I make a Unit Test for this if? If SBPL is a required dependency then it is easier.

[DavidB-CMU]

Mike wrote:
I agree with this entirely. However, I think these tests should be on SBPLPlanner and live in prpy. We should add or_sbpl as a <test_depend> like we did for the other planners that we test in prpy

[mkoval]

I suggest adding it as a <test_depend>. This is what we did for the other planners that are optional dependencies.