call _preset_args_changed instead of changing selection

[kecnry]

This PR is to avoid having to change the current footprint selection in order to force an update through _preset_args_changed

[gibsongreen]

This PR is to avoid having to change the current footprint selection in order to force an update through _preset_args_changed

Thank you, I do see what I was missing in `preset_args_changed'. I rebased my branch and visually testing it, and its resulting in buggy behavior. If I create 2 custom footprints with different ra/dec values, they are loading in the same location (until the overlay selected in the UI is changed, then it reloads in the correct location).

It isn't obvious to me why iterating through the exposed overlay.selected results in different behavior since the only other call would be change_overlay and there doesn't seem to be anything in there that would effect this specific behavior.

Irregardless I am putting together the regression test and see if I can get to the bottom of why this approach results in different behavior from going through exposed functionality.

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