Implement updateing the Image tags in Containers and Pod/Deployments supplied by user with image Digest

[santoshkal]

Currently, we enforce using versioned tags for containers in Dockerfile Base images and Deployment/Pod Containers and fail the validation results if the images use the latest tag.

To further improve the workflow and follow best practices in defining the containers, it's proposed to update the image tag with image Digest after the validation is complete. In this way instead of failing the validation for images/containers using the latest tag, we can update the image tag with the Digest of the latest image used.

So it would look like:

FROM nginx:latest
# Would be updated to 
 FROM nginx@sha256:xxxx

For Kubernetes Pods/Deployments:

containers:
- name: nginx
  image: nginx:latest

# Would now updated to 
containers:
- name: nginx
  image: nginx@sha256:xxxx