pytest: rework conftest.py to support solver/writer marker expressions

[jsiirola]

Fixes # .

Summary/Motivation:

Pyomo's existing pytest configuration supports marking solver tests using pytest.mark.solver(name), and then running those tests using a custom --solver name command line argument. However, the test selection was done by skipping tests at runtime and not deselecting the tests after collection. Further, the markers could not be used in "normal" marker expressions (because pytest does not support accessing positional arguments in marker expressions).

This PR redesigns how we handle solver markers:

• the positional argument is mapped to a keyword argument (id). This enables using markers expressions like solver(id='highs') to select tests based on the solver marker.
• an additional keyword argument (vendor) is also defined using a substring of id up to, but not including the first underscore. This supports selecting "all" tests for a vendor. For example solver(vendor='gurobi') will match gurobi, gurobi_direct, and gurobi_persistent solver markers.
• the --solver command line option is now translated into a marker expression (instead of relying on skipping tests at runtime)
• move the solver marker definition into the pyproject.toml (with all the other markers)

In addition, this PR:

• adds a writer marker that works analogously to the solver marker
• removes a number of unused pytest markers from pyproject.toml
• propagates the use of the solver marker through the solver tests in pyomo.solvers and pyomo.contrib.solver
• found a way to mark tests generated by paarameterized.expand

Changes proposed in this PR:

• (see above)

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[codecov]

Codecov Report

❌ Patch coverage is 90.32258% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.63%. Comparing base (5852a20) to head (c2ce299).
⚠️ Report is 15 commits behind head on main.

Files with missing lines	Patch %	Lines
conftest.py	90.32%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3854      +/-   ##
==========================================
+ Coverage   89.59%   89.63%   +0.04%     
==========================================
  Files         905      905              
  Lines      106006   106014       +8     
==========================================
+ Hits        94974    95030      +56     
+ Misses      11032    10984      -48     

Flag	Coverage Δ
builders	29.13% <87.09%> (+0.02%)	⬆️
default	85.95% <90.32%> (?)
expensive	35.60% <87.09%> (?)
linux	86.92% <ø> (-2.25%)	⬇️
linux_other	86.92% <ø> (ø)
oldsolvers	32.10% <87.09%> (+2.23%)	⬆️
osx	83.09% <ø> (ø)
win	85.15% <ø> (-0.01%)	⬇️
win_other	85.15% <ø> (-0.01%)	⬇️

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