Make Convergence object checks aware of solve type

[joshuahansel]

Motivation

The Convergence system in #28848 introduces Convergence objects with a checkConvergence() method. These objects are planned to work in several different contexts, such as:

• nonlinear solves
• steady-state detection
• fixed point solves

Some implementations of checkConvergence() will need to know which of these context the object is being used in, or at least throw an error if used in an ineligible context.

Design

A possible solution is to pass some kind of IterationType parameter to checkConvergence(), which could have values like IterationType::Nonlinear. It would be ideal to be able to have an extensible list of iteration types, but this is not essential.

Impact

Possible API changes.