Use 3-digit, x.x.x-style semantic versioning for `@since` tags of the `$rest_namespace` property in `WP_Post_Type` and `WP_Taxonomy`.
Add a `@since` note to `WP_REST_Taxonomies_Controller::get_item_schema()` for the `visibility` and `rest_namespace` properties.
The `rest_base` property was also added after the method was initially introduced, but that happened during the same release cycle, so it doesn't need a separate `@since` note.
Follow-up to [38832], [39191], [42729], [51959], [51961], [51962], [51964].
See #53399.
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