UI Tests for the extension (in nodejs)

[DonJayamanne]

Re-write of #4692

The original UI Tests were written in Python (that solution had issues due to the use of selenium driver).
The new version will be based on nodejs using the Chrome devtools protocol (puppeteer).

Broken into the following stages:

• Refactor pipelines into stages Refactor pipelines into stages #7430
• Add UI Tests to run smoke tests (enable just the smoke tests) WIP - UI Tests in nodejs #6717 (todo - break up PR).
• Add UI Tests to run UI Tests (enable just the stable UI Tests) WIP - UI Tests in nodejs #6717
• Add UI Tests to run UI Tests for other tests (there are a number of UI tests that are disabled).

[DonJayamanne]

Closing in favor of #6511