Content Types

[oscartbeaumont]

Successor of failed approach of #199

Work:

• [ ] Using futures joiners within resolver layer traits
• [x] Refactor StreamOrFut and its sub-futures together - This ends up being hard cause Future vs Stream
• [x] Replacing Stream with custom trait
• [ ] Solution for batch decoding using framing -> working w/ Typescript
• [ ] Solution for batch encoding using framing -> working w/ Typescript
• [ ] Introduce ContentType & ContentTypes trait + generics based on Rspc
• [ ] Using custom enum for Poll so custom values can be yielded through the chain (both up and down)
• [ ] Remove the input: Value arg through layer system

closes #173