Extend GeneratorParams.SetSearchOption to allow setting strings

[koepalex]

First of all, awesome library, it is fun to use 👏
It would be great extension to allow other types of search options for example string[].

Use case would be to pass stop words into the model (for example as defied by the HuggingFace TextGenerationApi parameter stop).

[natke]

Thank you for the suggestion @koepalex! I'm moving this into our new features area in Discussions