Tweaks to Support Workflows

[expede]

I'm having trouble expressing workflows that account for resources like timeouts and Wasm fuel limits using the current layout 😭 The core problem is that I don't want to mix resources into the Task level. I'd also like to avoid creating multiple signatures, but that's not as critical.

I think a minor tweak fixes this. I'm trying a few things, but I keep coming back to an earlier proposal. This is just a draft for now, but I want to work in the open, so here's the draft PR 😉

[expede]

Yeah, I'm fairly convinced that this is a requirement regardless of how we want to write worflows. The concern with the existing system is that you need to sign all of the sub-invoctaions because the resource limits are at the same level as the signature. This changes the CID, so you can't sign the Workflow wrapper at the same time without finding a hash cycle.

By pulling the auth to another layer, we get the flexibility to do nesting with a single signature without breaking the signature reference mechanism as it exists in v0.1.

I actually don't mind if the signature is subtyped or wrapped. I just need a struct that's everything minus the signature, and IPFS Schema doesn't have subtying/splats:

type Context struct {
  v    Semver
  run  &Task
  meta {String : Any}
  prf  [&UCAN]
}

-- Subtyped

type Invocation struct { -- Exactly the same as today
  ...Context
  auth &Authorization
}

-- Wrapped

type Invocation struct {
  ctx  Context -- could also be a Link, but this is closer to today
  auth &Authorization
}

The added bonus is that this also signs over all fields, and is really really clear about that fact

[expede]

Subsumed by #15