Pyomo.DoE bugfixes

[djlaky]

Fixes # .

1. Ensured square solve (e.g., fix the experiment inputs) when solving each scenario block.
2. Added self.tee to sequential compute FIM method

Summary/Motivation:

Fixing some bugs found in Pyomo.DoE over the past month.

Changes proposed in this PR:

• Adding fixing/unfixing of experimental design decisions to ensure a square solve for each finite difference scenario
• Added a reference to the internal tee value in the compute FIM methods

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[djlaky]

@smondal13, @adowling2

Bug we saw this morning that was fixed but not pushed.