Remove pyomo.duality and pyomo.core.plugins.transform.model

[jsiirola]

Fixes # .

Summary/Motivation:

This removes two {old, deprecated, poorly tested} pieces of Pyomo:

• pyomo.duality - this package has been completely superseded by:
  • pyomo.duality.lagrangian_dual (deprecated since 5.6.2) is completely replaced by pyomo.core.plugins.transform.lp_dual
  • pyomo.duality.collect is replaced by pyomo.repn.plugins.standard_form. This is a more generalized and robust implementation (and with simpler, easier to use return data types)
    • Note we never officially deprecated this module. That said, it is buggy and not documented. To our knowledge, no one in the wild is using this module (otherwise they should have been complaining about the bugs). As it is not core functionality and does not appear in the Book, this PR proposes deleting the module without deprecation. An alternative path would be to create a small wrapper around the standard_form writer that re-creates the old return types (which will resolve the bugs) and then immediately deprecate that method. Providing the deprecation path would be several hours of work.
• pyomo.core.plugins.transform.model (deprecated since 6.7.3) has been replaced by pyomo.repn.plugins.standard_form

Changes proposed in this PR:

• remove pyomo.duality
• remove pyomo.core.plugins.transform.model

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.

[blnicho]

There are a couple example py files used in these tests that are not deleted in this PR. I'm guessing they aren't being tested anywhere else so I wonder if they should be removed.

[jsiirola]

Good catch! Removed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.92%. Comparing base (509f0d1) to head (3b001b6).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3876      +/-   ##
==========================================
+ Coverage   89.68%   89.92%   +0.24%     
==========================================
  Files         908      901       -7     
  Lines      106764   106285     -479     
==========================================
- Hits        95750    95581     -169     
+ Misses      11014    10704     -310     

Flag	Coverage Δ
builders	29.19% <ø> (+0.11%)	⬆️
default	86.22% <ø> (?)
expensive	35.66% <ø> (?)
linux	87.38% <ø> (-1.80%)	⬇️
linux_other	87.38% <ø> (+0.23%)	⬆️
oldsolvers	28.11% <ø> (+0.11%)	⬆️
osx	82.70% <ø> (+0.21%)	⬆️
win	85.80% <ø> (+0.22%)	⬆️
win_other	85.80% <ø> (+0.22%)	⬆️

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