KEYCLOAK-839 Auth Server overlay enhancements


    For add-provider and update-server-config operations
        Add an overwrite option that allows you to replace an overlay.
        Add a redeploy option that redeploys the auth server after the overlay is uploaded.
    Add a list-overlays operation to see the uploaded overlays.
    Add a remove-overlay operation to remove an overlay.
    Remove the CLI snapshot jar. It is no longer needed now that the updated CLI has been released in the WildFly Core project.

Note: Above, "overlay" actually refers to overlay content. This is a provider jar, theme jar, or keycloak-server.json file that is uploaded to extend or configure an auth server.