Add a toggle to runMultiplePlp to skip diagnosis

[egillax]

I would prefer to be able to skip the diagnosis which is run when developing models using runMultiplePlp. It's taking a non-trivial amount of time and I've never looked at the output, although maybe I would for a clinical study. There are also certain inefficiencies how it's done. For example if you have 2 predictions problems and 3 classifiers. It will run the diagnosis 6 times (2x3). But as far as I can see you only need to run it once per prediction problem.

I'd like to have a toggle to turn it off. And would prefer actually the default for it to be off.

What do you think @jreps. I've also discussed this with @lhjohn and I believe he agrees.

[jreps]

I was thinking yesterday we can make it more optimized (e.g., if the model design is the same except for the model then they can share diagnostics currently but that may change if we add classifier specific diagnostics) but I think it should be there by default as it can help identify issues with the prediction design and all HADES analyses have diagnostics to help identify issues.

[egillax]

What issues will it identify?

[egillax]

If the goal is to identify issues in your design. Then I think it's in the wrong place currently. Currently while it runs before runPlp it doesn't affect it in any way. I think a more reasonable workflow would be:

1. diagnosePlp and look at results
2. adjust design if problematic
3. develop model