Close figures from StandardPlotOutput.py

[bbean23]

There's a bug that occurs with TKinter when previously opened windows aren't closed correctly. I believe that StandardPlotOutput.py is openening plots and then leaving them open, under the assumption that matplotlib will close the plots automatically. This is generally true, and works most of the time, but sometimes can cause issues such as are found here: https://github.com/sandialabs/OpenCSP/actions/runs/10358781025/job/28673746085?pr=154