Solver Refactor Part 1: Introducing the new solver interface

[mrmundt]

Fixes #1030 (but not entirely)

Summary/Motivation:

This is a relatively large PR that introduces a refactored solver interface (placed in contrib as it is not yet the default behavior). Ideally, the intent behind this PR is to:

1. Standardize behavior for solvers
2. Make behavior more intuitive
3. Incorporate necessary features such as timers, logging, etc.
4. Create a better foundation for new interfaces

Changes proposed in this PR:

• New base solver interface for direct and persistent solvers, based on APPSI
• Changed structure for options and results
• Framework to remove unclear/obsolete/inefficient options (such as keepfiles)
• Documentation for solver interfaces (new and exciting)
• Backwards compatibility mapping to allow users to use both the new and old interfaces at the same time
• Minor bug fixes that were caught while refactoring

Legal Acknowledgement

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1. I agree my contributions are submitted under the BSD license.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.

[blnicho]

I'm still going through this but here are some initial comments

[jsiirola]

I think we should re-think this API and not pass the results in / out of this function. I would argue for this to be a parser that returns the parsed data, and populating a results object is the responsibility of the caller. This would also remove the somewhat confusing passing in / out of results objects.

[mrmundt]

I agree. It's "rough" but not "as rough as it used to be" right meow.