Uses scipy's Haar measure functions

[nquesada]

Scipy implements the generation of Haar random unitary and orthogonal matrices, thus there is no need to implement them internally.

[codecov]

Codecov Report

Merging #731 (fb11e28) into master (9a9a352) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #731      +/-   ##
==========================================
- Coverage   98.33%   98.33%   -0.01%     
==========================================
  Files          78       78              
  Lines        9603     9602       -1     
==========================================
- Hits         9443     9442       -1     
  Misses        160      160              

Impacted Files	Coverage Δ
strawberryfields/utils/random_numbers_matrices.py	100.00% <100.00%> (ø)

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