Change data passed into `add_component` to be a glue Component to attach units

[brechmos-stsci]

From @nmearl in spacetelescope/cubeviz#501 (comment):

The data passed to the add_component method is a simple array-like. This needs to be changed to an explicitly glue Component object in order to attached associated units. This would need to be done in specviz's glue data viewer.

[nmearl]

Fixed with #680.