ROX-15724: rename kubeconfig contexts for easier merge

[parametalol]

Having a kubeconfig with:

contexts:
- name: ctx1
  context:
    user: username
    cluster: clustername
users:
- name: username
clusters:
- name: clustername
current-context: ctx1

The rename-kubeconfig-ctx.jq script renames the entities as the following:

contexts:
- name: clustername // <- ctx1
  context:
    user: username@clustername // <- username
    cluster: clustername
users:
- name: username@clustername // <- username
clusters:
- name: clustername
current-context: clustername // <- ctx1

[parametalol]

The script file is not found, need some work.