Basic Smoke Testing of the extension in the PR/Release Pipelines

[baronfel]

It looks like we can define tests to programmatically operate a test vscode with the extension loaded. We should add some basic smoke tests and run them during the pipeline to prevent regressions like we experienced with 5.7.2.

This may look like exporting some interfaces from the extension to allow testability?

Resources:

• https://code.visualstudio.com/api/working-with-extensions/testing-extension