Add support for the VKE HA control plane option

[optik-aper]

Description

• adds the HA option flag to the kubernetes/VKE create
• adds the HA field to the output for GET and LIST
• adjusts some help text

Related Issues

Checklist:

• [x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• [x] Have you linted your code locally prior to submission?
• [x] Have you successfully ran tests with your changes locally?

[github-actions[bot]]

Unit Tests and Coverage

Show Output

``` ? github.com/vultr/vultr-cli/v2 [no test files] ```

Pusher: @optik-aper, Action: pull_request_target

[github-actions[bot]]

Unit Tests and Coverage

Show Output

``` ? github.com/vultr/vultr-cli/v2 [no test files] ```

Pusher: @optik-aper, Action: pull_request_target

[github-actions[bot]]

Unit Tests and Coverage

Show Output

``` ? github.com/vultr/vultr-cli/v2 [no test files] ```

Pusher: @optik-aper, Action: pull_request_target