Support for Nextera and other library preparations

While discussing preparation sheets, @AmandaBirmingham @charles-cowart and I realized that the present shotgun library preparation page only allows for Kapa Hyper Plus:

I spoke with @ghsmu414 and he confirmed that, while the majority of preparations are Kapa Hyper Plus, we do still use Nextera. In addition, library preparations beyond Nextera and Kapa Hyper Plus may be used in the future.

It would be beneficial to allow for specifying Nextera kits. But a more general interface here, which allows the user to create a new kit type, may be the most ideal.