Deprecate robot/util -> planToConfiguration() [WIP]

[sniyaz]

This PR removes planToConfiguration() from robot/util, and updates the corresponding function in ConcreteRobot to use a snap planner.

We actually don't remove the method completely from robot/util, just the header: it's needed elsewhere in the .cpp file.

TODO/WIP:

1. Should we use the normal ConfigurationToConfiguration planner, or the DART version? Both work fine here and the normal version requires less cruft, so I've gone with that. LMK your thoughts!
2. Should we construct the planner in ConcreteRobot -> planToConfiguration, or have a planner member var in ConcreteRobot? The reason I didn't do this is because the MetaSkeleton passed to the planner constructor(s) may not match the metaSkeleton argument of planToConfiguration().

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[brianhou]

Should this be closed in favor of #588?