Update multistart solver, add method for multistart NLP initialization

[stephenscini]

Fixes # .

Summary/Motivation:

Additional method in devel/initialization to use multistart optimization as a way for initializing nonliner models.

Changes proposed in this PR:

• Updating contrib/multistart solver for reproducibility, and adding support for new solver interface.
• Adding support for uniform, lhs, and sobol sampling within the multistart solver
• Adding method to devel/initialization

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[stephenscini]

Opening PR, but still in active development. Dependent on #3991 first as it includes those changes.

[stephenscini]

Note for 7/21 Dev meeting

Method implemented with support for new solver interface. All original tests passing locally.

Tasks before ready for review:

• It looks like there is an issue with changing the SolverFactory version in a different place, which I will address.
• Try and simplify interface, check with mentors.
• Add tests for new functionality

[stephenscini]

@michaelbynum @blnicho I think this is ready for review. Please take a look when you have a chance. Thanks!

[stephenscini]

Note from 08/25 dev meeting: Not necessarily a bad design choice but technically precedent in Pyomo is to allow users to change the solver during solve after initialization. Worth future discussion.

[stephenscini]

Note from 08/25 dev meeting: Not necessarily a bad design choice but technically precedent in Pyomo is to allow users to change the solver during solve after initialization. Worth future discussion.

Followed precedent and added back config option. Also adjusted so availability checks subsolver, and is rechecked during solve in case of change.

[stephenscini]

@michaelbynum @blnicho
Can the osx/3.14 be rerun please? Not sure why it failed. Thanks!