Issue and PR Editors should allow tagging users with @ sign

### Feature summary

Bring in similar api's and user list and suggestions to editor as web Pr and issue editor

### What problem are you trying to solve?

When adding issue of PR comments its often needed to tag users or teams. This is fundamental to comments and editor experience in web allows that. This should be same experience on the app editor.

### Proposed solution

Interface for editor should be same as it is on the web which is

### Workflow impact

You can achieve this by clickin the green issue or pr link on top of the app that opens the web browser which requires you to then refresh the app to see the issue comment again after leaving the app and perform action in browser.

### Installation context

_No response_

### Additional context

_No response_