feat(cosign): implement cosign for signing docker images in CI

[abhisheksr01]

Description

Implement sigstore/cosign for adding provenance and signing the container image in GitHub Action CI.

Use Case

Once the image is built in the CI and should be signed in the GHA CI.

Proposed Solution

Implement and document the use of cosign in the CI. Document why it's needed.

Benefits

Secure use of container images.

Example

Additional Information

https://github.com/sigstore/cosign