feat: dagger module

[migmartri]

Dagger module of the Chainloop client that can be used to attest and collect pieces of evidence from your Dagger pipelines.

Note: This module requires Chainloop v0.60.0 or newer which contains support for stateless attestations #494

The attestation process starts with its initialization (attestation-init), then adding as many materials/pieces of evidence as needed (attestation-add), and finally, signing and pushing the attestation to the Chainloop control plane (attestation-push).

This module implements all those functions so they can be executed either via the dagger CLI (see demo below) or by being imported by other Degger modules.

$ dagger functions
┃ Name                 Description                                                                                                     
┃ attestation-add      Add a piece of evidence/material to the current attestation                                                     
┃ attestation-init     Start the attestation crafting process                                                                          
┃ attestation-push     Generate, sign and push the attestation to the control plane                                                    
┃ attestation-reset    Mark current attestation process as canceled or failed. --trigger = "failure" | "cancellation" (default: "failur
┃ )                                                                                                                                    
┃ attestation-status   Check the status of the current attestation     

Demo using the CLI

dagger-demo.mp4

Closes #501

[danlishka]

LGTM! I would add a bit more on contracts in the documentation - we do not mention contracts at all, but they are an important part of the attestation process provided by Chainloop.