[Depends on #3695] Observer gurobi refactor

[michaelbynum]

Summary/Motivation:

This PR refactors the gurobi interfaces to achieve two goals:

• reduce duplicate code
• use the new contrib.observer package

Changes proposed in this PR:

• create a directory for gurobi now that there are 4 files
• create a base class for all of the interfaces that use gurobipy, making the direct and persistent interfaces more consistent (e.g., tc_map, postsolve, solve, mipstart)
• modify the persistent interface to use the contrib.observer package
• add mipstart functionality to gurobi direct and gurobi minlp
• add a minimum gurobipy version to the direct interface (addMConstr was not added until version 9)
• simplified some of the persistent interface

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 65.59817% with 601 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.54%. Comparing base (8397f66) to head (43a864f).

Files with missing lines	Patch %	Lines
...contrib/solver/solvers/gurobi/gurobi_persistent.py	28.65%	488 Missing ⚠️
pyomo/contrib/observer/model_observer.py	90.70%	61 Missing ⚠️
...ontrib/solver/solvers/gurobi/gurobi_direct_base.py	83.84%	42 Missing ⚠️
...ntrib/solver/solvers/gurobi/gurobi_direct_minlp.py	66.66%	5 Missing ⚠️
...omo/contrib/solver/solvers/gurobi/gurobi_direct.py	95.23%	3 Missing ⚠️
pyomo/contrib/observer/component_collector.py	96.82%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3698      +/-   ##
==========================================
- Coverage   89.23%   85.54%   -3.70%     
==========================================
  Files         907      911       +4     
  Lines      104817   105454     +637     
==========================================
- Hits        93536    90213    -3323     
- Misses      11281    15241    +3960     

Flag	Coverage Δ
builders	29.19% <25.58%> (+0.03%)	⬆️
default	85.37% <65.59%> (?)
expensive	35.69% <25.58%> (?)
linux	?
linux_other	?
osx	?
win	?
win_other	?

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