Bugfixes and testing of linear templates

[jsiirola]

Fixes # .

Summary/Motivation:

This PR is primarily adding more comprehensive testing of templatizing (and compiling) linear models. As part of flusing out the tests, this resolves a number of issues / bugs in the templatizer, the linear template compiler, and in general Pyomo:

General Pyomo changes

• Rework Param.extract_values to return defaultdict for Params with default values
• Provide a specialized InvalidConstraintError exception for constraints that cannot be emitted to the solvers
• Use SetOf when iterating over IndexedComponent objects indexed by non-finite Sets
• SetOf.dimen should return UnknownSetDimen (not 0) if the underlying reference has no data

Updates to the templatizer

• Leverage attempt_import to break circular dependencies in template_expr
• Catch UnknownSetDimen when iterating over template generators and treat like jagged sets
• Expand (do not templatize) expressions with sum() that do not sum over generators
• Expand (do not templatize) expressions with sum() whose generator doesn't create a template index
• Expand (do not templatize) expressions with sum() that appear to iterate over things other than Pyomo Set objects

Updates to the linear template compiler

• remove check_duplicates and remove_fixed_vars options (this is not more efficiently implementable through sparse matrix operations0
• rework expression builders to be more testable and (slightly) more efficient
• Support IndexedComponent.Skip
• Resolve issue compiling constraints indexed by non-finite Sets

Changes proposed in this PR:

• (see above)

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.

[codecov]

Codecov Report

❌ Patch coverage is 96.77419% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.55%. Comparing base (f2d23a5) to head (9645d4c).
⚠️ Report is 602 commits behind head on main.

Files with missing lines	Patch %	Lines
pyomo/core/base/constraint.py	85.71%	1 Missing ⚠️
pyomo/core/base/param.py	91.66%	1 Missing ⚠️
pyomo/repn/linear_template.py	98.70%	1 Missing ⚠️
pyomo/repn/plugins/lp_writer.py	50.00%	1 Missing ⚠️
pyomo/repn/plugins/standard_form.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3781      +/-   ##
==========================================
+ Coverage   89.48%   89.55%   +0.07%     
==========================================
  Files         904      904              
  Lines      105385   105436      +51     
==========================================
+ Hits        94299    94426     +127     
+ Misses      11086    11010      -76     

Flag	Coverage Δ
builders	29.04% <16.77%> (+<0.01%)	⬆️
default	83.67% <96.77%> (?)
expensive	35.53% <22.58%> (?)
linux	86.86% <96.77%> (-2.35%)	⬇️
linux_other	86.86% <96.77%> (+0.09%)	⬆️
oldsolvers	29.69% <16.77%> (+<0.01%)	⬆️
osx	83.01% <96.77%> (+0.09%)	⬆️
win	85.08% <96.77%> (+0.08%)	⬆️
win_other	85.08% <96.77%> (+0.08%)	⬆️
xpress95	?

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