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

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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 96.17834% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.34%. Comparing base (4ce6049) to head (3d8e302).

Files with missing lines	Patch %	Lines
pyomo/core/base/param.py	86.66%	2 Missing ⚠️
pyomo/core/base/constraint.py	85.71%	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   89.24%   89.34%   +0.09%     
==========================================
  Files         907      907              
  Lines      104818   104866      +48     
==========================================
+ Hits        93548    93690     +142     
+ Misses      11270    11176      -94     

Flag	Coverage Δ
builders	29.15% <16.56%> (+<0.01%)	⬆️
default	85.87% <96.17%> (?)
expensive	35.71% <21.65%> (?)
linux	86.79% <96.17%> (-2.22%)	⬇️
linux_other	86.79% <96.17%> (+0.10%)	⬆️
osx	82.92% <96.17%> (+0.10%)	⬆️
win	85.03% <96.17%> (+0.09%)	⬆️
win_other	85.03% <96.17%> (+0.09%)	⬆️

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