tree command to display all the supply chain security artifacts

[developer-guy]

Description

It'd be nice to have a tree command to display all the supply chain security artifacts such as SBOM, Attestation, Signature, etc. All of these are stored in an OCI registry along with the image itself with separated tags for SBOM .sbom, for Attestation .att, for Signature .sig, so, we'll be adding a tree command to view all of them in a nice formatted way like the following:

$ cosign tree <img> # if the user supplies a tag we'll be visualizing the data only for the tag, if not, we'll be summarizing all of the tags that the image has.

devopps/hello-world:latest
--> sha256:9fc31a8935dfdac754401cac99a6812a932fac70a49c003baecc2c2be0ba4454
    --> sha256-9fc31a8935dfdac754401cac99a6812a932fac70a49c003baecc2c2be0ba4454.sig
    --> sha256-9fc31a8935dfdac754401cac99a6812a932fac70a49c003baecc2c2be0ba4454.att
	--> sha256-9fc31a8935dfdac754401cac99a6812a932fac70a49c003baecc2c2be0ba4454.sbom

devopps/hello-world:v1
--> sha256:3267cad69a9cfc40c239f12c2589740642323772a445c837838a7f4d2507e605.
    --> sha256-3267cad69a9cfc40c239f12c2589740642323772a445c837838a7f4d2507e605.sig
    --> sha256-3267cad69a9cfc40c239f12c2589740642323772a445c837838a7f4d2507e605.att
	--> sha256-3267cad69a9cfc40c239f12c2589740642323772a445c837838a7f4d2507e605.sbom

[dlorenc]

Sure, this could either go under the triangulate command or as it's own!