Move to Ipopt v2

[bknueven]

Pyomo 6.7.0 includes changes to the NL writer. We should consider the following:

• [ ] Scaling factors are now applied before the model is written to NL. This should make a large portion of the WaterTAP Ipopt wrapper redundant, and incidentally would close #298.
• [ ] With the new linear presolver, it seems like some flowsheets/tests which were not solvable with MuMPS are now solvable. We should remove the pytest marker requires_idaes_solver everywhere an add back in only where needed.

Either of these changes would make pyomo>=6.7.0 a requirement for WaterTAP, but this constraint may be redundant to the extent we depend on the latest release of IDAES.

[lbianchi-lbl]

If I understand correctly, it looks like these features are valuable to WaterTAP regardless of IDAES, and therefore I'd be in favor of adding a "standalone" (i.e. independent from the transitive requirement through idaes-pse) pyomo >= 6.7 requirement.