[DNM see note below] Add PSACT custom resource and tests

[a-blender]

Issue: https://github.com/rancher/terraform-provider-rancher2/issues/1189

Problem

Add PSACT template resource https://ranchermanager.docs.rancher.com/how-to-guides/new-user-guides/authentication-permissions-and-global-configuration/psa-config-templates to the provider.

Solution

What was added

• [x] pod_security_admission_configuration_template resource and data source
• [x] name, description, defaults, and exemption subfields within the template designed to fit the Rancher backend + ValidateFunc for default modes.
• [x] Update tests
• [x] Update docs and config examples

Testing

Engineering Testing

Manual Testing

Tested creating, modifying, and removing a custom PSACT template on a 1.27 rke2 cluster. All tests successful. Also tested creating a template with bad data and this fails.

Note: Modifying / removing PSACT exemptions (usernames, runtime classes, or namespaces) requires the template to be reapplied to the kube API server for this change to take effect. If a cluster is already using a template, you must remove the reference, update the template, then re-add the template to the cluster.

_Note: Rancher webhook manages the machine selector file sources created for a reference to a PSACT template. A user has to add a ignore_changes to their tf config or tf will try to add a file source back to the provisioning spec on template deletion._

Automated Testing

QA Testing Considerations

Regressions Considerations

[a-blender]

All tests are working here except for cluster deletion. If you try to remove all infra (cluster + custom template) at the same time, template deletion will error out because the cluster (and reference to the template) is not removed yet. A retry needs to be added to the PodSecurityAdmissionConfigurationTemplate 'Delete' func to retry deleting the template a few times instead of returning a static err.

[kkaempf]

closing stale PRs. If you still intend to work on this, please reopen.