Adding tally filter type option to statepoint get_tally

[shimwell]

This PR adds a filter_type arg to the Statepoint.get_tally function

This is useful for getting mesh tallies when the user just has access to the statepoint.

When the user only has access to the statepoint results and not the python script is it not conveniently pass in the actual filter object to the existing filter argument as one has to reconstruct the mesh filter with the same mesh and filter_id.

I have also added tests for getting tallies using this new filter_type and a few other methods as I could not find a dedicated test for this function.

Fixes # (issue)

Checklist

• I have performed a self-review of my own code
• I have followed the style guidelines for Python source files (if applicable)
• I have made corresponding changes to the documentation (if applicable)
• I have added tests that prove my fix is effective or that my feature works (if applicable)

[shimwell]

I beileve the CI was failing due to coveralls being down. Worked fine after a rerun 🎉

[GuySten]

Looks good @shimwell.