Can we use `ParticleAtom.extractParticleClosestToCenter()` instead of `BANModel.getParticleToReturn`

[zepumph]

Promoting TOOD made while investigating https://github.com/phetsims/build-a-nucleus/issues/105.

This is a newish function, so it could replace this older code.

[Luisav1]

This can't be done because of two things:

• getParticleToReturn returns the particle closest to the particles creator node while extractParticleClosestToCenter gets the particle closest to the center of the atom
• extractParticleClosestToCenter also extracts the particle, it removes it from the particle atom which we don't want being done until after the particle is animated away from the particle atom. Closing.