Extend Diagnostics Tools to support Grey Box models

[andrewlee94]

Fixes None

Requires Pyomo/pyomo#3870

Summary/Motivation:

The current diagnostics tools do not support grey box models, and either do not work at all or give misleading results. This PR extends most methods supported by the DiagnosticsToolbox to work with models which include ExternalGreyBoxBlocks. These changes require the updates in Pyomo/pyomo#3870 and require the ExternalGreyBoxBlock to set build_implicit_constraint_objects=True.

Current exclusions are:

• SVDToolbox - this quite possibly will work with the changes implemented here, but I lack the time and knowledge to test it.
• DegeneracyHunter - similarly, this might also work with the changes implemented here.
• Minimum infeasible set: this is a Pyomo tool and would need to be fixed there by someone who knows the code.

Changes proposed in this PR:

• Update all statistics methods to correctly collect variables and implicit constraints from grey box blocks.
• Update Jacobian tools to collect Jacobian information from implicit constraints.

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