Update the PyROS Separation Priority Ordering Interface

[shermanjasonaf]

Summary/Motivation:

Update the PyROS solver interface for specification of constraint separation priorities.

Changes proposed in this PR:

• Add support for detection of separation priorities from Suffix components with local name "pyros_separation_priority"
• Deprecate the optional argument separation_priority_order
• Acknowledge, where applicable, separation priorities mapped to (the name of) any Var or Constraint component declared on the model. Thus, for example, constraints derived from Var bound specifications can be prioritized by mapping priorities to Var components
• Allow None to be specified as a priority for equality and inequality constraints that are not to be robustly enforced. These constraints are enforced subject to only the nominal uncertain parameter realization, and are therefore excluded from the separation problems. Note also that equality constraints with a priority of None are, therefore, not reformulated via coefficient matching or discretization, where otherwise applicable
• Add to the PyROS online documentation a section that explains the interface for specifying constraint separation priorities

TODO

• Update version number, changelog (including deprecation warning and online docs logging example)

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[shermanjasonaf]

@jas-yao @natalieisenberg