tctl: Add support for rm okta_assignment

[kopiczko]

Backports:

• [v18] tctl: Add support for rm okta_assignment #62698

changelog: Added tctl support for removing okta_assingment internal resource should it be needed.

[zmb3]

This is fine, but one of the quality goals I want us to focus on going forward is completeness.

It feels like users may be confused if we allow tctl rm foo but not tctl get foo.

Additionally, we're in the middle of converting the tctl resource commands to the new handler format (#60370). This PR adds new resources to the old way of doing things, making more work for us to go back and convert.

Any reason not to spend a little bit more time adding support for okta_assignment using the new resources pattern and supporting more verbs other than rm?

[kopiczko]

Just saying, we support tctl get okta_assignment for a very long time now. I'll see how much time is to rework this, but it should be noted this PR is to solve a support issue and I think it has a marginal impact on the command conversion itself.

[zmb3]

Just saying, we support tctl get okta_assignment for a very long time now.

Gotcha, I didn't realize that was the case. I'm fine with this for a quick fix then.

(As a side note, I noticed that running tctl get okta_assignment against an OSS cluster returns an unknown service error instead of an error explaining that this is an enterprise feature.)

[milos-teleport]

@kopiczko a gentle holiday ping. This seems to be ready to be merged.

[kopiczko]

I'm merging this now as is to help with fixing the customer's issue. I made a note to revisit and align it with the new approach during one of my support shifts.

[backport-bot-workflows]

@kopiczko See the table below for backport results.

Branch	Result
branch/v18	Failed