Add support for known hosts on ssh secret in Fleet Git Repo

[nwmac]

Summary

Fixes #11236

Occurred changes and/or fixed issues

This PR enhances the SelectOrCreateAuthSecret component so that for the SSH secret type, it can also support the known_hosts field. Note that this is non-standard in that known hosts is not part of the standard k8s SSH secret type. This is only used by Fleet.

The Fleet GitRepo use of the above control enables the new field, so that when creating a GitRepo, you can specify the known hosts information.

Lastly, the secret view is updated, so that if an SSH secret has the known_hosts data key, we will show this on the detail screen and also allow the user to edit via the config screen.

Areas or cases that should be tested

Creating a Git Repo with a secret with known hosts. Validate that the secret that is created has the known_hosts data field and validate that this can be edited in the secrets screen.

Screenshot/Video

The updated auth secret control:

The edit dialog for this control when you click the three dots:

Secrets edit view when known_hosts is present in an SSH secret:

EDIT @torchiaf

Screencast.from.2025-01-30.18-09-07.webm

Checklist

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[torchiaf]

@nwmac I cleaned-up the code and added Codemirror and some layout improvements.
@edenhernandez-suse I'll fix the SSH fields dimensions in the GitRepo edit page ASAP or we could also do it in #13162

[edenhernandez-suse]

@torchiaf as you prefer, if you want to close this one we can apply the changes as a part of the other issue, I'm fine with it.

[aalves08]

I was able to create a Fleet gitRepo with SSH type secret and the known hosts info. Was also able to check the information on the secrets detail view and edit it successfully with the secrets edit view. Nothing stands out codewise, so LGTM 🙏