Remove PySP

[jsiirola]

Fixes #N/A

Summary/Motivation:

This PR removes PySP from Pyomo, as it is now distributed as a separate package (see https://github.com/Pyomo/pysp).

Note: because this removes PySP, pyomo.contrib.parmest is currently not tested (waiting either for resolution of #1778 or the creation of a GHA job that installs PySP).

Changes proposed in this PR:

• Remove PySP (code, documentation, and examples)
• Remove the phpyro solver manager

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.

[DLWoodruff]

I was planning to work on #1778 on Friday. Recommend merging this PR and then we can verify that #1778 might be an answer.

[codecov]

Codecov Report

Merging #1819 (58716f8) into master (5afbdfc) will increase coverage by 3.17%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1819      +/-   ##
==========================================
+ Coverage   74.93%   78.11%   +3.17%     
==========================================
  Files         638      554      -84     
  Lines       92256    70162   -22094     
==========================================
- Hits        69136    54809   -14327     
+ Misses      23120    15353    -7767     

Impacted Files	Coverage Δ
...mo/contrib/parmest/examples/semibatch/semibatch.py	4.51% <0.00%> (-87.97%)	⬇️
pyomo/contrib/parmest/scenariocreator.py	23.43% <0.00%> (-76.57%)	⬇️
pyomo/contrib/parmest/graphics.py	7.74% <0.00%> (-74.54%)	⬇️
.../parmest/examples/rooney_biegler/rooney_biegler.py	0.00% <0.00%> (-72.73%)	⬇️
...o/contrib/parmest/examples/semibatch/scencreate.py	24.13% <0.00%> (-72.42%)	⬇️
.../parmest/examples/reactor_design/reactor_design.py	0.00% <0.00%> (-72.23%)	⬇️
pyomo/opt/parallel/pyro.py	18.34% <0.00%> (-69.73%)	⬇️
pyomo/pysp/__init__.py	33.33% <0.00%> (-66.67%)	⬇️
pyomo/contrib/parmest/parmest.py	11.28% <0.00%> (-61.43%)	⬇️
pyomo/solvers/plugins/smanager/pyro.py	23.01% <0.00%> (-59.53%)	⬇️
... and 117 more

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[blnicho]

PySP is also mentioned in the main Pyomo README. We might want to edit this section:

Further, Pyomo has also proven an effective framework for developing high-level optimization and analysis tools. For example,
the PySP package provides generic solvers for stochastic programming. PySP leverages the fact that Pyomo's modeling objects
are embedded within a full-featured high-level programming language, which allows for transparent parallelization of
subproblems using Python parallel communication libraries.