Enhance types for Node and Edge envionments (#64454)
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### What?
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### What?
This enhances the typings in the `BaseServer`, `NextNodeServer`, and
`NextWebServer` to simplify types for request and responses across the
entire server. Rather than relying on manual environment checks only as
the source with error-prone type casts, this adds basic guards (albeit
naive) that assert the typings depending on the runtime environment
variables. This greatly enhances the typings used across the servers as
the servers no longer use the `as` keyword when working with these
request and response types.
This is a precursor to future planned work to further split the
different rendering runtimes to assist with code elimination and
framework organization.
### Why?
As a step to utilizing these more unified types, the `app-render.tsx`
(App Pages rendering pipeline) has been modified to instead accept the
abstract `BaseNextRequest` and `BaseNextResponse` types. This is a
precursor to future work to split the streaming behaviour based on the
runtime environment (ie, in Node.js, we can utilize the native streams
instead of web streams, which offer significant performance gains).
### How?
The server types were modified to be generic, allowing the three server
implementations to have their types flow safely between the different
methods. This enables us to only reference the `NodeNextRequest` within
the `NextNodeServer`, and the `WebNextRequest` within the
`NextWebServer` for example.
🎥 [Loom
Video](https://www.loom.com/share/76af2225cf0246d0b4f609ab3e35fff9?sid=c948a919-ac9e-4571-8a75-bd9d0a0776e2)
Closes NEXT-3102
