feat!: add KeyringRequest.origin

[ccharly]

TODO.

[danroc]

Note: we are setting the origin to metamask here regardless of the real origin.

Do you have an idea how we are going to send the real origin? Also, will this new field break the existing Snaps?

[ccharly]

Good point 🤔 I wrongly assumed we were using those methods when interacting through the MetaMask UI, but this will also be called externally with call like eth_sign*, in which case, the true origin would not be metamask.

And yes, this new field might also break existing Snaps. I don't know else I could trick that. My only idea right now would be to "version the API", and have a runtime check on the version, something like:

getVersion() {
  const { version } = await this.#snapClient
    .withSnapId(snapId)
    .getVersion();
    
  if (!version) {
    return ...; // First version when we introduced the new `getVersion`?
  }
}

But even know, we cannot check which methods are being implemented on a Snap, which would result in a runtime error for this ⬆️.

And adding a version won't solve everything, cause we would have type-issue here to (here we need to pass origin, or we need to have another variant type for submitRequest with an optional origin, that won't scale well IMO..)