feat(security): add cosign to sign image

[whg517]

ref: #55

Since we are building the container in a container environment with buildah, we need to get the buildah container to support cosign signing and push the signing result to the mirror repository.

We need to do some extra work in the way we use cosign instead of github-action:

1. Install the cosign command in the buildah container so that it can be used to sign the container after it is built.
2. Passing oidc information from the github action environment into the buildah container allows cosign to keyless sign based on github authentication in the buildah container
3. Fixed cosign not being able to use buildah cached authentication information directly in the buildah environment. ref: cosign sign does not use local image registry credentials sigstore/cosign#587 (comment)

Once the heredoc issue with buildah in ubuntu 24.04 environment is fixed, we can simply and easily complete these tasks using only github-action based mode.

[whg517]

@lwpk110 ready to review