Derive _kraus_ from _apply_channel_

[iamsusiep]

Add fallback strategy to the kraus protocol to obtain Kraus values from _apply_channel_.
Attempted as a very-last strategy, because it is computationally expensive.

Resolves #5921

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.68%. Comparing base (bdcf704) to head (a72564a).
Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #7434    +/-   ##
========================================
  Coverage   98.68%   98.68%            
========================================
  Files        1091     1093     +2     
  Lines       96945    97179   +234     
========================================
+ Hits        95670    95904   +234     
  Misses       1275     1275            

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[iamsusiep]

cc: @daxfohl

[daxfohl]

Looks great!

[iamsusiep]

@pavoljuhas @vtomole @senecameeks PTAL, thanks!

[pavoljuhas]

LGTM with a couple of small changes.

[pavoljuhas]

Thank you for contributing this!