Resolve dynamic initialization of Param values

[jsiirola]

Fixes #4009; supersedes #4030

Summary/Motivation:

#4009 identified a bug where some Params were not being correctly initialized when instantiated outside of Param.construct(). While Params with default values were being correctly initialized, _getitem_when_not_present was not checking if the initializer (rule= / initialize=) could have provided a value (which is the case for constant initializers and initializers that call out to general functions).

This PR resolves the issue by also checking the rule for initial values when creating / returning param values outside of construct()

Changes proposed in this PR:

• Update Param default= handling to leverage the Initializer infrastructure
• Update _getitem_when_not_present to check the rule before falling back on the default.
• Add tests (including updating some DAE tests that now no longer raise exceptions)

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[codecov]

Codecov Report

❌ Patch coverage is 98.38710% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.13%. Comparing base (170f653) to head (f425201).

Files with missing lines	Patch %	Lines
pyomo/core/base/param.py	98.38%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4048      +/-   ##
==========================================
+ Coverage   89.96%   90.13%   +0.16%     
==========================================
  Files         917      917              
  Lines      109282   109298      +16     
==========================================
+ Hits        98311    98511     +200     
+ Misses      10971    10787     -184     

Flag	Coverage Δ
builders	29.12% <19.35%> (+<0.01%)	⬆️
default	86.13% <98.38%> (?)
expensive	35.09% <25.80%> (?)
linux	87.66% <98.38%> (-1.81%)	⬇️
linux_other	87.66% <98.38%> (+0.17%)	⬆️
oldsolvers	28.01% <19.35%> (-0.01%)	⬇️
osx	83.11% <98.38%> (-0.01%)	⬇️
win	85.42% <98.38%> (-0.01%)	⬇️

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