Feature Request: Add a Dequeue Button

Summary

It would be great to have a dequeue button directly in the Mergify browser extension. This would allow users to remove a pull request from the merge queue without having to leave the browser or interact with the Mergify dashboard or API manually.

Motivation

Currently, if you want to dequeue a PR, you need to either:

• Use the Mergify dashboard
• Post a comment with a Mergify command
• Use the Mergify API

Having a dequeue button in the extension would make this much more convenient and keep the workflow entirely within the GitHub UI.

Proposed Solution

Add a "Dequeue" button alongside the existing queue-related actions in the extension. Ideally it would appear on the PR page when the PR is currently in a merge queue, and clicking it would trigger the dequeue action via the Mergify API.

Additional Context

This would be a nice quality-of-life improvement, especially for teams that frequently need to reprioritize or remove PRs from the queue.

Start by locating the extension's existing queue-related actions and its Mergify API integration. Verify how PR-page actions determine queue membership and how the dequeue request is triggered. Done means a Dequeue button appears for queued PRs and removes the PR through the API without using the dashboard, comments, or manual API calls.