weak lensing encoder shear updates

[shreyasc30]

This PR makes the following weak-lensing and DC2-related changes:

• allows users of the dc2 class to pull the entire set of PSF parameters for the truth match galaxies while maintaining flexibility to just use the median
• subsequent updates to lensing dc2 to support the above workflow and expose PSFs in the tile catalog for use in image normalizers
• Novel ResNet-like network structure for weak lensing, along with ResNet and ResNeXt blocks
• Notably, the ability to have a residual connection via 1x1 convolution even when changing dimensions, which previous blocks did not have
• conversion of shear_1 and shear_2 to Normal Factors and temporary removal of convergence from being predicted
• subsequent updates to the encoder, plots, metrics, and config files to support the above

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 1 line in your changes missing coverage. Please review.

Project coverage is 76.16%. Comparing base (0907a16) to head (a13010c).

Files with missing lines	Patch %	Lines
bliss/surveys/dc2.py	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1072      +/-   ##
==========================================
- Coverage   76.17%   76.16%   -0.02%     
==========================================
  Files          22       22              
  Lines        3077     3079       +2     
==========================================
+ Hits         2344     2345       +1     
- Misses        733      734       +1     

Flag	Coverage Δ
unittests	76.16% <85.71%> (-0.02%)	⬇️

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[jeff-regier]

Looks good otherwise

[jeff-regier]

Thanks for the revision