[ParU] Use boolean and enum types instead of integers

[gruenich]

Is your feature request related to a problem? Please describe.
The interface as defined by ParU.hpp uses signed integer int64_t where boolean or enum types would be better.
Example for variables that should be boolean: ParU_Control->scale, Examples for variables that should be enums: ParU_Symbolic->strategy, ParU_Control->paru_strategy`

Describe the solution you'd like
Introduce boolean and enum types. Technically, this is an interface change and should happen before releasing SuiteSparse 7.4.0. Internally, more changes like the named above might improve readability and semantic.

Describe alternatives you've considered
Sticking to the way it is.

Additional context
Overall, the interface follows a C style, less C++ way of doing an interface.

[DrTimothyAldenDavis]

Thanks for the feedback. Yes, the API does need some polishing. That's why I've tagged it as 0.1.0, since the API will change soon. I plan to spend some time rethinking the interface after I release Suitesparse 7.4.0. I think it needs more work than just the integer/ bool types though. Those do need some rework as you've pointed out. But it's likely I will make more changes.

If I make these changes for ParU 0.1.0 that you suggest, I will probably find more API breaking changes to make when I get the time to polish it for a 1.0.0
release.

So my preference is to release it as is and rewrite the API later

[DrTimothyAldenDavis]

I'll leave this issue open though, so I don't forget any of your suggestions.