add option to mark levels in display_ee

[douglase]

current behavior when utils.display_ee is called is to label 50, 80, and 95% encircled energy. This breaks when a level is not encircled by the PSF. This PR adds the option for the user to specify custom levels with a keyword levels. if the keyword is not specified then there is no change to the existing behavior.

[codecov]

Codecov Report

Patch coverage: 20.00% and project coverage change: -2.18 ⚠️

Comparison is base (1dccb8d) 74.84% compared to head (acfe870) 72.66%.

❗ Current head acfe870 differs from pull request most recent head 4ee9666. Consider uploading reports for the commit 4ee9666 to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #540      +/-   ##
===========================================
- Coverage    74.84%   72.66%   -2.18%     
===========================================
  Files           18       18              
  Lines         6499     6479      -20     
===========================================
- Hits          4864     4708     -156     
- Misses        1635     1771     +136     

Impacted Files	Coverage Δ
poppy/utils.py	53.29% <20.00%> (-0.25%)	⬇️

... and 10 files with indirect coverage changes

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[BradleySappington]

@douglase I just pushed changes to develop that will fix your failing tests. If you fetch/merge we can move forward with this PR.

[mperrin]

I merged the latest develop into this and have pushed it here, which should hopefully get all the tests passing.

[mperrin]

👍
For the record, most of the changes in this PR as seen in GitHub are other recent PRs which I just merged into this to update it to the current develop. The only actual changes specific to this PR are those in utils.py, which I reviewed and approve.