Make progress notifications clickable

[asavaritayal]

In cases where it could take a long time to execute a task, make the progress notification clickable so users can navigate to the terminal to view the steps being executed.

/cc @fiveisprime @gbowerman

[ejizba]

Currently not possible - tracking issue in VS Code: microsoft/vscode#60979

[ejizba]

We do this now with "View Output" links