Include kubectl command metadata in http request headers

[pwittrock]

Enhancement Description

• One-line enhancement description (can be used as a release note): kubectl adds http headers with the subcommand name, which flags were specified and a session id.
• Kubernetes Enhancement Proposal: https://github.com/kubernetes/enhancements/tree/master/keps/sig-cli/859-kubectl-headers
• Discussion Link: https://groups.google.com/g/kubernetes-dev/c/y4Q20V3dyOk/m/ozSUR3dJDQAJ
• Primary contact (assignee): @soltysh @pwittrock
• Responsible SIGs: cli
• Enhancement target (which target equals to which milestone):
  • Alpha release target (x.y): 1.21
  • Beta release target (x.y): 1.22
  • Stable release target (x.y):

[pwittrock]

cc @kubernetes/sig-api-machinery-misc
cc @kubernetes/sig-cli-misc
cc @soltysh
cc @deads2k

[kacole2]

@pwittrock can you please update the original post with the correct formatting so we have consistency?

# Enhancement Description
- One-line enhancement description (can be used as a release note):
- Kubernetes Enhancement Proposal: (link to kubernetes/enhancements file, if none yet, link to PR)
- Primary contact (assignee):
- Responsible SIGs:
- Enhancement target (which target equals to which milestone):
  - Alpha release target (x.y)
  - Beta release target (x.y)
  - Stable release target (x.y)