Publish Extension to ADS marketplace on new release

[SteveL-MSFT]

Summary of the new feature

As part of our release process, we should be able to leverage AzDevOps pipelines to auto-publish to ADS marketplace (creating a PR to update their extension) whenever we publish a new stable release.

[andyleejordan]

Whoops, thought this was to the general VS Code marketplace, which we need to do first. Then we can do the ADS marketplace (however, it may always be manual because they need to verify version support before taking new releases).