Remove WP Rocket's options from not public post types

[piotrbak]

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Describe the bug When the post type is not public we should not display:

1. Clear this cache button on the view listing all CPT entries
2. Clear This Post button from top menu while editing the post
3. Purge this URL button from the top menu while viewing the post when logged-in as admin

Per: https://github.com/wp-media/wp-rocket/issues/5010#issuecomment-1157295620

Backlog Grooming (for WP Media dev team use only)

• [ ] Reproduce the problem
• [ ] Identify the root cause
• [ ] Scope a solution
• [ ] Estimate the effort

[arunbasillal]

Thanks for opening this @piotrbak.

• If post type is not public, the post will not have a view when logged-in as admin. So point 3 will not exist for these posts.

• If the post type uses classic editor, then these posts will still have the Clear Cache button in the Publish meta box. (Screenshot available in https://github.com/wp-media/wp-rocket/issues/5010#issuecomment-1157295620)