Add DetConSLoss and DetConBLoss

[liopeer]

Description

• adds the losses DetConBLoss for Detcon with BYOL and DetConSLoss for Detcon with SimCLR
• adds tests
• adds the classes to the docs
• makes them available as lightly.loss.DetConBLoss and lightly.loss.DetConSLoss

How has it been tested?

• non-distributed: against values gathered from the original JAX implementation
• distributed: only if it runs through and creates scalar value

Attachments

• docs screenshot
  

[codecov]

Codecov Report

Attention: Patch coverage is 97.70115% with 2 lines in your changes missing coverage. Please review.

Project coverage is 85.25%. Comparing base (356ae56) to head (3211b88).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
lightly/loss/detcon_loss.py	97.67%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1771      +/-   ##
==========================================
+ Coverage   85.08%   85.25%   +0.16%     
==========================================
  Files         162      163       +1     
  Lines        6747     6834      +87     
==========================================
+ Hits         5741     5826      +85     
- Misses       1006     1008       +2     

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[liopeer]

Tests have been completely re-written.

• now use proper mocking to simulate the distributed behaviour
• randomized testing against the original implementation (jax.numpy -> numpy) and a few additional small changes (change details are as comments in the code)

[guarin]

Left some minor comments but overall looks very good! Let's get this merged :)

[guarin]

LGTM!