Option to mute extension notifications

[JCKodel]

Issue Type: Feature Request

A lot of extension authors think it is a good idea to raise a notification for each operation we do on their extensions (for example: TT-Processor raises two notifications for every T4 template being processed, resulting in a huge spam of notifications that we're forced to dismiss manually).

It would be awesome if we could just silence all notifications from a certain extension (the notification already knows what extension invoked it, so it should not be hard).

Of course, we should be able to choose what kind of notification we want do dismiss: information, warning or error. In my case (TT-Processor), warning is used as a progress "I'm transforming your file", info is used for conclusion "I have transformed your file" and errors shows T4 compilation errors (that I would mantain, but the same output goes to OUTPUT window, so, potato potato =P)

VS Code version: Code 1.46.1 (cd9ea64, 2020-06-17T21:13:20.174Z)
OS version: Windows_NT x64 10.0.19041

[gjsjohnmurray]

/duplicate of #41767