Fix issues in cubed-sphere regridding

[yuanjianz]

Name and Institution (Required)

Name: Yuanjian Zhang Institution: WashU

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Describe the update

Fixed bugs about cube-sphere regridding formatting mentioned in #310

Expected changes

1. Now cube-sphere regridding in file_regrid would have correct shape of value array for single level plotting in single_panel.
2. Now compare_single_level will automatically choose the higher resolution between two standard cube-sphere grids, and also having correct unflipped absdiff and fracdiff. (see the figure below)
3. Now will not trigger renaming error when 2D data (Emissions, column AODs) that needs regridding is passed to compare_single_level.
4. delete code for quiting benchmark (which is already included in dev branch)

Reference(s)

None

Related Github Issue(s)

#310