Bounding box function and mirrorGrid changes

[anilyil]

This PR replicates the changes in #58. The old PR was closed w/o merging because of conflicts I did not want to deal with.

Here, I added the method to get the bounding boxes from grids, which can be then used to fine tune the cartesian grid coordinates in: mdolab/pyhyp#65 I also made slight modifications to the mirror grid call because it was not working for what I needed to do. Finally, a new function to mirror surface grids (the default mirror only works on volume)

Purpose

Expected time until merged

few days

Type of change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (non-backwards-compatible fix or feature)
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Documentation update
• Maintenance update
• Other (please describe)

Testing

Checklist

• I have run flake8 and black to make sure the Python code adheres to PEP-8 and is consistently formatted
• I have formatted the Fortran code with fprettify or C/C++ code with clang-format as applicable
• I have run unit and regression tests which pass locally with my changes
• I have added new tests that prove my fix is effective or that my feature works
• I have added necessary documentation

[anilyil]

I changed the mirror behavior so that the _mirror grids have the same trailing index as the original grid. I find this more useful when I am trying to map which block mirrors to which in tecplot etc

[codecov]

Codecov Report

Merging #59 (7868db1) into main (1040111) will increase coverage by 0.09%.
The diff coverage is 84.00%.

@@            Coverage Diff             @@
##             main      #59      +/-   ##
==========================================
+ Coverage   21.79%   21.89%   +0.09%     
==========================================
  Files           3        3              
  Lines        2271     2279       +8     
==========================================
+ Hits          495      499       +4     
- Misses       1776     1780       +4     

Impacted Files	Coverage Δ
cgnsutilities/cgns_utils.py	0.00% <0.00%> (ø)
cgnsutilities/cgnsutilities.py	27.79% <91.30%> (+0.11%)	⬆️

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[sseraj]

Looks good overall. One comment though: