PETSc Tweaks

[dallan-keylogic]

Changes proposed in this PR:

-Only include active blocks when constraints/variables are collected for PETSc solve
-Rename snes_solver option to initial_solver because the point of the option is to permit use of initial solvers besides snes
-Add symbolic solver labels to initial condition problem
-Get rid of unused list fix_derivs

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[andrewlee94]

Seeing as we are pushing to get backward compatibility tests into place, this look like a place where we are going to need backward compatibility options and warnings. I.e. we need to keep the old options around, and have them raise deprecation warnings if they are used before sending the value to the new argument (and raise an exception if both old and new are provided).

[dallan-keylogic]

I was hoping that this feature being around for only a month and not making it into a major release would prevent that from being necessary. Perhaps not, however.

Edit: snes_solver has been around only for a month. However, snes_options has been around longer.

[andrewlee94]

If it is that new then we are probably OK, but we need to double check that is the case.

[dallan-keylogic]

Got the deprecation logged for snes_options. Ready for a new review.

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (b01bc20) 76.71% compared to head (51a4391) 76.71%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1235   +/-   ##
=======================================
  Coverage   76.71%   76.71%           
=======================================
  Files         382      382           
  Lines       61182    61188    +6     
  Branches    11289    11291    +2     
=======================================
+ Hits        46935    46940    +5     
- Misses      11814    11817    +3     
+ Partials     2433     2431    -2     

Files Changed	Coverage Δ
idaes/core/solvers/petsc.py	85.65% <100.00%> (+0.65%)	⬆️

... and 1 file with indirect coverage changes

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[eslickj]

I wanted to make this change when I added the snes_solver option, since it's not necessarily an SNES solver anymore, but I didn't want to break anything. Once @andrewlee94 gets his deprecation warning, I'm good with this.

[andrewlee94]

Looking good - just a couple of minor comments to avoid some edge cases and be more inline with other deprecations.

[andrewlee94]

We generally use logger = idaeslog.getLogger(__name__) for this - using __name__ gives more granularity and avoids hard-coded string constants. Also, Pyomo has a deprecation warning function for things like this:

from pyomo.common.deprecation import deprecation_warning

deprecation_warning(
    msg=msg, logger=logger, version="2.0.0", remove_in="3.0.0"
)

[andrewlee94]

LGTM