feat: coffea for histogram production

[alexander-held]

This adds a coffea backend for template histogram production. Currently incomplete and work in progress.

related:

• coffea-to-cabinetry
• Efficient production of template histograms for statistical analysis coffea#469
• Passing custom fileset metadata through run_uproot_job coffea#479, which could lead to a cleaner interface

[codecov]

Codecov Report

Merging #216 (0b2d2ee) into master (40120c2) will decrease coverage by 2.48%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##            master     #216      +/-   ##
===========================================
- Coverage   100.00%   97.51%   -2.49%     
===========================================
  Files           23       24       +1     
  Lines         1881     1929      +48     
  Branches       305      313       +8     
===========================================
  Hits          1881     1881              
- Misses           0       47      +47     
- Partials         0        1       +1     

Impacted Files	Coverage Δ
src/cabinetry/contrib/coffea_wrapper.py	0.00% <0.00%> (ø)
src/cabinetry/templates/__init__.py	100.00% <ø> (ø)
src/cabinetry/templates/builder.py	97.14% <0.00%> (-2.86%)	⬇️

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