Frontend: Allow project owners to delete secrets permissions

Why are we doing this work

This is a follow up to #470367 (closed).

Owners should be able to delete existing secret permissions from the settings. Maintainers can view these settings, but they cannot delete permissions.

Relevant links

• Parent epic
• Closed Experiment/Beta Secrets Manager Placement Design SSOT - Figma link
• Backend API issue
• Frontend: Define permissions
• Design issue

Non-functional requirements

• Feature flag: secrets_manager and ci_tanukey_ui
• Testing

Implementation plan

Design Notes

There is no separate design, but we'll follow the pattern in #470404[Delete_Secret__Detail_page_.png].

See #503311[3_EntitiesAdded.png] (comment 2474794008):

Just a confirmation modal is fine, no need to enter anything to confirm - similar to how we handle removing a user from a project. The UI text in the modal would be:

Remove <type> (user, group, or role)

Are you sure you want to remove <item>?

[Cancel] [Remove <type>]

Verification steps

1. Set up openbao on your gdk.
2. Enable the Secrets Manager on gdk.
3. Go to your project settings (Settings > General) and expand Visibility, project features, permissions to view the permissions table.
4. Create permissions and then verify that you can delete them.

• Deleting requires the user to confirm via a confirmation modal first
• There should be a toast message that provides feedback that the deletion is successful.