Free invariant HTTP codecs

[rossabaker]

Replaces the renderer and parser of the core HTTP types with a free algebra. This can then be interpreted into:

• Cats Parse for nice error and composition in String contexts
• A prospective binary parser that gets right to ByteBuffer
• Renderer for compatibility with today
• A prospective fast encoder that goes straight to ByteBuffer
• Similar for Netty's ByteBuf, if that backend wants to make its own codecs instead of intermediate passes through Netty's

A path away from #6915. A different take on #5356.

[rossabaker]

Going to be blocked on typelevel/cats#2620. The FreeInvariantMonoidal works for product types, but we need an invariant betwixt Alternative and Decidable to model sum types.

Early performance returns are good. Renderer is a bit slower, but still fast. Cats Parse is actually slightly (but consistently!) faster than before!

[rossabaker]

Mastodon conversation reminds me of prior art for JSON in xenomorph: https://github.com/nuttycom/xenomorph

[danicheg]

tiny nitpick: somewhere in http4s, we use implicit lazy vals. Shouldn't we apply it here also?

[SystemFw]

In terms of api expressiveness, you might also want to look at https://systemfw.org/dynosaur/#/schema
the library was originally inspired by xenomorph as well, but it ended up making different tradeoffs