Apply black to doc directory py files

[mrmundt]

Fixes (Partly) #329

Summary/Motivation:

This is the first in a relatively long string of PRs to apply PEP8 standards via black to Pyomo. We are following the standard used by IDAES except that we are adding the -S option: Don't normalize string quotes or prefixes and the -C option: Don't use trailing commas as a reason to split lines.

NOTE: All changes are NFC.

Full command used: cd doc && black -S -C .

Changes proposed in this PR:

• Apply black to the doc directory py files

Legal Acknowledgement

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1. I agree my contributions are submitted under the BSD license.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[codecov]

Codecov Report

Base: 87.03% // Head: 86.97% // Decreases project coverage by -0.06% ⚠️

Coverage data is based on head (7302ab9) compared to base (8fe21bb).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2728      +/-   ##
==========================================
- Coverage   87.03%   86.97%   -0.06%     
==========================================
  Files         771      771              
  Lines       86162    86162              
==========================================
- Hits        74993    74943      -50     
- Misses      11169    11219      +50     

Flag	Coverage Δ
linux	84.14% <ø> (+<0.01%)	⬆️
osx	73.59% <ø> (ø)
other	84.32% <ø> (ø)
win	81.50% <ø> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pyomo/util/subsystems.py	89.13% <0.00%> (-8.70%)	⬇️
...ontrib/appsi/utils/collect_vars_and_named_exprs.py	93.75% <0.00%> (-6.25%)	⬇️
pyomo/core/base/external.py	95.43% <0.00%> (-3.16%)	⬇️
pyomo/contrib/appsi/writers/nl_writer.py	84.39% <0.00%> (-2.32%)	⬇️
pyomo/repn/plugins/ampl/ampl_.py	81.40% <0.00%> (-1.86%)	⬇️
pyomo/core/expr/compare.py	96.52% <0.00%> (-1.74%)	⬇️
pyomo/contrib/appsi/solvers/ipopt.py	88.51% <0.00%> (-0.34%)	⬇️
pyomo/repn/plugins/nl_writer.py	93.49% <0.00%> (-0.33%)	⬇️
pyomo/contrib/appsi/base.py	84.94% <0.00%> (-0.26%)	⬇️
pyomo/core/expr/visitor.py	93.40% <0.00%> (+0.15%)	⬆️
... and 1 more

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[blnicho]

This doesn't apply black formatting to code blocks in rst files. Is this something we should worry about? I think the answer is "no".

[mrmundt]

@blnicho - I agree that I don't think we care about applying black to rst code blocks.