standardize on Greenwood config as single source for prerender behavior for all renderer plugins

[thescientist13]

Type of Change

Enhancement

Summary

Coming out of conversations in #1170 , it was questioned what the Lit SSR plugin's prerender configuration offers, since it is somewhat presented as an alternative to Greenwood's default WCC powered SSR renderer. However, at this time, the Lit SSR plugin doesn't really distinguish pages using Lit from those not using Lit and so only understands LitElemeent anyway, so I don't think there's anything achieved with having two options for the same thing, since it doesn't achieve any meaningful behavior / value.

In fact, on the Lit SSR website docs page, we demonstrate just using the top-level prerender option in greenwood.config.js

Details

So I think it would make sense that for renderer plugins they should also mirror this behavior, so we might as well just use the value of prerender from greenwood.config.js and Renderer plugins can just leverage that to manage their behavior.

We'll also want to update the website docs for this Plugin API - https://greenwoodjs.dev/docs/reference/plugins-api/#renderer