Embed dependencies in setup.py

[jsiirola]

Fixes # N/A

Summary/Motivation:

Pyomo currently has dependencies scattered across the GHA / Jenkins builders, .readthedocs-requirements.txt, and setup.py. This PR moves all dependency specification into setup.py, and updates the GHA and RTD builders to pull dependencies from setup.py. As part of the rework, setup.py now specifies three "extras" targets for managing optional dependencies:

• tests for dependencies needed to run the Pyomo unit tests (currently, nose, coverage, parameterized, and pybind11)
• docs for dependencies needed to build the RTD documentation
• optional for packages (available on PyPI) on which Pyomo has an optional dependency.

With this, a reasonable approximation of the old pyomo-extras package is:

pip install 'pyomo[tests,docs,optional]`

The challenge with this PR is that conda does not play well with pip requirements. The complexity here is to provide a bridge whereby our conda builds can interrogate setup.py to get the list of packages that pip would have otherwise installed (and then conda can install from conda-forge).

Changes proposed in this PR:

• add extras_requires to setup.py
• add a new command python setup.py dependencies to get lists of required and optional dependency packages
• rework the GHA builders to get dependencies from setup.py
• rework RTD configuration to use a .readthedocs.yaml configuration and get documentation requirements from pyomo[docs]

Legal Acknowledgement

By contributing to this software project, I have read the contribution guide and agree to the following terms and conditions for my contribution:

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.

[mrmundt]

Alternative way to do this: in the env section, set EXTRAS=test,docs,optional and then for slim, change that. I have no strong opinions, but it's fewer lines.

[codecov]

Codecov Report

Merging #2017 (6bb2dd3) into main (baf79e5) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #2017      +/-   ##
==========================================
- Coverage   82.70%   82.69%   -0.01%     
==========================================
  Files         592      592              
  Lines       73352    73352              
==========================================
- Hits        60663    60661       -2     
- Misses      12689    12691       +2     

Impacted Files	Coverage Δ
pyomo/common/dependencies.py	98.75% <ø> (ø)
pyomo/solvers/plugins/solvers/ASL.py	89.70% <0.00%> (-1.48%)	⬇️

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