feat(cli): Add token authentication support for connect kube helper

[Kaldei]

Description

Adds support for consuming password-type credentials when connecting to Kubernetes targets using boundary connect kube helper command.

When a password credential is brokered through Boundary, the command will now pass it as a bearer token to kubectl using the --token flag.

Tested with both Static and Vault credential stores against an actual Kubernetes cluster.

PCI review checklist

• I have documented a clear reason for, and description of, the change I am making.
• If applicable, I've documented a plan to revert these changes if they require more than reverting the pull request.
• If applicable, I've documented the impact of any changes to security controls.
  Examples of changes to security controls include using new access control methods, adding or removing logging pipelines, etc.

Reason for change: Enable connect kube helper to authenticate to Kubernetes clusters using credentials brokered.

Revert plan: Can be fully reverted by reverting this PR.

Security control impact: No changes to security controls. Follows existing pattern from other connect commands (SSH, Postgres, Redis).