[Feature][Kubectl-plugin] Make flags override yaml file for kubectl ray job submit #3639
Description
See #3627 (comment).
Expected behavior is that if filename and flags are both provided by the user, then take the filename as base to construct a RayJob object, and then override the values in that object with flags.
So if user provided a yaml file with headCPU set to 2 in it, and specifies the flag --head-cpu 3, then the resulting RayJob should set head CPU to 3.