Consider activating this extension only for specific events

[DonJayamanne]

Currently this extension gets activated everytime, even when opening a plain text file. This results in unnecessary resource usage on end user machines.

Orignally filed here https://github.com/microsoft/vscode/issues/138481

Please could you update the activationEvents in package.json to activate only when necessary:

• E.g. when a file postgres is opened or the like More information can be found here https://code.visualstudio.com/api/references/activation-events

[Borvik]

This is being investigated for the next major version of the extension - though there might be some releases between now and then to prepare the way for other features.