rpk: introduce license warnings messages

[r-vasquez]

This PR introduces a license warning message whenever a user runs an rpk command that uses the admin API and the cluster has enterprise features with an invalid license.

Example

$ rpk cluster health
You're using Enterprise features in your Redpanda cluster: [partition_auto_balancing_continuous]. These features require a license, visit https://docs.redpanda.com/current/get-started/licenses for more information.
CLUSTER HEALTH OVERVIEW
=======================
Healthy:                          true
...

Backports Required

• [ ] none - not a bug fix
• [ ] none - this is a backport
• [X] none - issue does not exist in previous branches
• [ ] none - papercut/not impactful enough to backport
• [ ] v24.2.x
• [ ] v24.1.x
• [ ] v23.3.x

Release Notes

Improvements

• rpk will now warn you when you are running enterprise features without a license.

[r-vasquez]

/dt

[vbotbuildovich]

ducktape was retried in https://buildkite.com/redpanda/redpanda/builds/55258#0192307e-65a5-41d9-b158-6e0768776609

ducktape was retried in https://buildkite.com/redpanda/redpanda/builds/55342#01923506-c2cb-45b9-be04-412df2942212