Provide IO Types for MoleculeShapesModel schema

[samreid]

From https://github.com/phetsims/phet-io/issues/1774, we should create IO Types that can correctly capture the schema of the state objects.

    // TODO: Provide IO Types to specify these schemas instead of ObjectLiteralIO, see https://github.com/phetsims/phet-io/issues/1774
    // Shaped like this:
    // {
    //       position: Vector3.Vector3IO,
    //       velocity: Vector3.Vector3IO,
    //       isLonePair: BooleanIO,
    //       element: NullableIO( StringIO ),
    //       isCentralAtom: BooleanIO
    //     }
    groups: ArrayIO( ObjectLiteralIO ),

    // Shaped like this:
    //    {
    //     a: NumberIO,
    //     b: NumberIO,
    //     order: NumberIO,
    //     length: NumberIO
    //   }
    bonds: ArrayIO( ObjectLiteralIO ),

[jonathanolson]

Handled above, closing.