feat(amazonq): add setup for ui-tests (#7597)

This is the initial commit for UI Tests using the framework
vscode-extension-tester. It instantiates the VSCode instance which opens
Amazon Q and goes through some basic flows to login. This is done using
the [VSCode-Extension-Tester
Framework](https://github.com/redhat-developer/vscode-extension-tester/wiki/).
(Note: It is missing full authentication and stops working once Amazon Q
needs to open the browser).

**To run this test**

1. First compile the test files
`npm run testCompile`
2. Then run the test setup
`node_modules/.bin/extest setup-tests`
2. Then run the script (NOTE: this js file should be generated when you
compile the test files)
`node_modules/.bin/extest run-tests
aws-toolkit-vscode/packages/amazonq/dist/test/e2e/amazonq/VET.test.js`

For information why each dependency / webpack change is needed, please
see
[here](https://quip-amazon.com/lCuBAOGibHzm/UI-Tests-PR-Explanation).

Demo Video:

https://github.com/user-attachments/assets/f1c6e59f-d4e3-4ae0-a164-1da389ec1339

---

- Treat all work as PUBLIC. Private `feature/x` branches will not be
squash-merged at release time.
- Your code changes must meet the guidelines in
[CONTRIBUTING.md](https://github.com/aws/aws-toolkit-vscode/blob/master/CONTRIBUTING.md#guidelines).
- License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

Author: laura-codess