Add support for KNITRO

[eminyouskn]

No description provided.

[metab0t]

The implementation is high quality, especially your design of CallbackEvaluator.

An annoying issue is that when using the license you sent to me, knitro outputs

##### This license is only intended for use by POI CI/CD. #####
##### License is valid until Mar 01, 2027 #####

during pytest tests and interrupts the display in terminal. Is there any method to turn off this when running pytest?

[eminyouskn]

Thanks. You can remove this by setting the variable ALM_SILENT=1 in the terminal before running the tests. By the way let me do a small refactor and cleaning before you merge it.

[eminyouskn]

@metab0t I finished my cleaning.

[metab0t]

LGTM, I will merge it to see whether the CI is happy.

[metab0t]

@eminyouskn Please fix the compilation errors on Linux and mac according to the latest CI logs. It seems to be related to constexpr initialization and some type conversions.

[eminyouskn]

@metab0t thanks for merging. Taking a look at it now.

[metab0t]

@eminyouskn It turned out to be small issues where constexpr string is not supported by old compilers. They are fixed now.

I notice that some documentation should also be modified to reflect the added support for KNITRO, and you can add them in subsequent PRs.

[eminyouskn]

Nice thank you again!