Add function for loading translations

[volkov0aa]

It's more logical for the library than for user code to know
where the library's translations are located and how to load them.

[DamirPorobic]

I'm not sure about this one. I agree that the library should take care of it's own stuff but a problem that I run into is that depending on the binaries the translation files are located differently, like for Windows they are in a directory next to executable, for AppImages and Snaps I think the path differs also. I have now some logic in ksnip that finds the translation files which would not work with this function.

And why a function, why not a method?

[DamirPorobic]

Oh, sorry, I was not reading carefully, you look already at the variable that ksnip sets. This might be working for me. But still, why not a method?

[volkov0aa]

• translations apply to the entire library, not to a single class
• kImageAnnotator::loadTranslations() is shorter than kImageAnnotator::KImageAnnotator::loadTranslations()