No way to reset re-authentication.

## Problem
Cannot relaunch or cancel re-authentication.

## Steps to reproduce the issue

1. Go to the Amazon Q extension on VScode.
2. Close authentication.
3. Go back to VScode.

## Expected behavior
Expect to be able to cancel current re-auth and relaunch re-auth.
But instead the "authentication in progress" will show, but the cancel button will still be greyed out.

## System details (run `AWS: About` and/or `Amazon Q: About`)

- OS: macOS Sequoia Version 15.7.3
- Visual Studio Code version: 1.107.1
- AWS Toolkit version:
- Amazon Q version: 1.106.0

Reproduce the problem in the Amazon Q extension for VS Code by closing authentication and returning to the editor. Trace the re-authentication flow to determine why the cancel control remains disabled; done means a user can cancel the current re-authentication and launch it again.

Written by the indexing model from the issue text.