Support @owner role

**Is your feature request related to a problem? Please describe.**
As a head of editors, I want editors to have a specific permission that can edit/delete their own articles so that an author cannot delete an article written by the other author.

**Describe the solution you'd like**
Currently, Admin UI has only two roles `Full access` and `Manage only`. We want Admin UI to have `editor` role that can write an article and update/delete only their own articles. That'd be similar to `@owner` permission.

**Describe alternatives you've considered**
We might can follow Wordpress's Roles and Capabilities which are called `Super Admin`, `Administrator`, `Editor`, `Author`, `Contributor` and `Subscriber` roles. More detail here: https://wordpress.org/support/article/roles-and-capabilities/

**Additional context**
A developer in the community are asked to implement more flexible roles which is described in the above and they needed to look for the other option as the role permission control was the blocker.

The issue identifies the Admin UI roles and the desired @owner behavior, but names no files, tests, or entry points. Start by locating the role and article-permission implementation, then define completion as an editor being able to create articles and update or delete only their own articles.

Written by the indexing model from the issue text.