Update cuemod init workflow

[santoshkal]

Currently cuemod init command looks for the value provided in the --tool flag and supports k8s, argocd, tektoncd, crossplane, and clusterapi tools.

It is proposed to enhance the above workflow to also accept OCI artifact URLs to create Cue workspace.
The artifact stored in the OCI registry should contain the following minimum requirements for creating a Cue workspace:

.
├── cue.mod
└── policy.cue

The cue.mod subdirectory Must contain all the upstream APIs in Cue format for the technology we intend to work with.

[santoshkal]

closed in #60