Cross correlators for alignment

[malika576]

• HoloParams class
• Correlator class with different types of correlators to align two images, on bright field, phase image, or gradient of phase.

Contributor Checklist:

• I have added myself to the creators.json file
• I have added a changelog entry for my contribution
• I have added/updated documentation for all user-facing changes
• I have added/updated test cases

[codecov]

Codecov Report

Attention: Patch coverage is 10.16949% with 159 lines in your changes missing coverage. Please review.

Project coverage is 24.17%. Comparing base (3e31dcb) to head (8508c99).
Report is 10 commits behind head on master.

Files with missing lines	Patch %	Lines
src/libertem_holo/base/align.py	0.00%	148 Missing ⚠️
src/libertem_holo/base/reconstr.py	62.06%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #69      +/-   ##
==========================================
- Coverage   26.76%   24.17%   -2.59%     
==========================================
  Files          10       11       +1     
  Lines         340      517     +177     
  Branches       23       27       +4     
==========================================
+ Hits           91      125      +34     
- Misses        245      388     +143     
  Partials        4        4              

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