Set start state to state space before creating vector field

[dqyi11]

This is only one line change so I did not create an issue.

In creating MoveEndEffectorOffsetVectorField, mStartPose is initialized from the current end-effector pose. https://github.com/personalrobotics/aikido/blob/master/src/planner/vectorfield/MoveEndEffectorOffsetVectorField.cpp#L32
We shall update the position of metaSkeleton before creating the vector field so that the start pose of the planning matches mStartPose. If not, it might start with a big deviation when the given startState is very different with current state of meta skeleton.

This is a fix to #426

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[jslee02]

It'd be great if we have a simple regression test for this.

[dqyi11]

Yes, maybe adding a test case when the start state is very different from the current state of meta skeleton.

[codecov]

Codecov Report

Merging #456 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #456   +/-   ##
=======================================
  Coverage   78.89%   78.89%           
=======================================
  Files         258      258           
  Lines        6303     6303           
=======================================
  Hits         4973     4973           
  Misses       1330     1330

Impacted Files	Coverage Δ
src/planner/vectorfield/VectorFieldPlanner.cpp	78.18% <100%> (ø)	⬆️