Refactor DOI table

[jdddog]

Refactors the DOI table:

• Moved the real Unpaywall data into its own struct.
• Moved COKI generated data into the coki struct.
• Add Black OA to coki.oa.colors based on whether DOI is in SciHub.
• Removed MAG from DOI table.
• Removed Elastic export tables.
• Updated test data for oa web workflow.
• Made Unpaywall test data not cover all outputs from Crossref Metadata, which is how the datasets work in reality.

[codecov]

Codecov Report

Patch coverage: 94.82% and project coverage change: -0.17% ⚠️

Comparison is base (afd3453) 95.80% compared to head (85e7d17) 95.64%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #171      +/-   ##
===========================================
- Coverage    95.80%   95.64%   -0.17%     
===========================================
  Files           19       19              
  Lines         4649     4589      -60     
  Branches       624      614      -10     
===========================================
- Hits          4454     4389      -65     
- Misses         122      127       +5     
  Partials        73       73              

Files Changed	Coverage Δ
...observatory_workflows/workflows/oa_web_workflow.py	96.06% <ø> (ø)
...ic_observatory_workflows/workflows/doi_workflow.py	95.47% <50.00%> (-1.42%)	⬇️
academic_observatory_workflows/model.py	97.25% <96.42%> (-0.53%)	⬇️

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[keegansmith21]

Looks good Jamie! I just had a question about a line, but feel free to merge when ready