Add Sprig templates for code generation

I'm planning on taking on #1521 to make it a bit easier to generate your own templates.

To make writing templates easier in general, I'd also like to import Sprig and add it to the functions used for the templates. I've been using them in my templates for some time via a fork. Many of the added functions are VERY useful for navigating the OAPI structs and the extensions Ive added.

Wanted to discuss before I PR if there are any questions or potential issues.