Simple Aperture Photometry: Recalculation breaks after Subset is edited

[Jdaviz-Triage-Bot]

Reporter: pllim

As reported in #1409 (review) . Workflow to reproduce:

1. Calculate aperture photometry as usual.
2. Now go back to the aperture subset, put it in edit mode, and move it to another star that you know will give a completely different answer.
3. Press calculate again without touching the aperture dropdown menu in the plugin.
4. Notice that the Subset info update in the Subset info plugin, but aperture photometry result still same as the old Subset.

This is because the plugin is not listening to subset edit event. @kecnry proposed potential fix at #1409 (comment) . Probably want to add a new unit test to prevent regression too.

🐱

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DISCLAIMER: This issue was autocreated by the Jdaviz Issue Creation Bot on behalf of the reporter. If any information is incorrect, please contact Duy Nguyen