Return updated/created/saved model from Future

[zdnk]

Given this code where Client is Model and struct:

        return try request.fromInput(to: Client.self)
            .save(on: request)
            .map {
                return try Client.Output(
                            id: $0.requireID(),
                            platform: $0.platform,
                            role: $0.role,
                            campaignId: $0.campaignId,
                            lastModifiedAt: $0.lastModifiedAt()
                )
            }
            .encode(status: .created, for: request)

The code will fail on requireID() because current implementation of Future.save(on:) returns the model that was passed to it, meaning the ID is still nil.

This PR fixes this scenario and return the return value from corresponding CRUD operations on Model like save(on:) etc.

[twof]

Assuming we're cool with potentially source breaking, I'm in favor of this.

[0xTim]

This definitely looks like a bug/oversight

[penny-coin]

Hey @zdnk, you just merged a pull request, have a coin!

You now have 1 coins.