The ARB editor extension provides language support for ARB files used for translating Flutter apps.

Since VS Code has removed recommending extensions based on file extension we should consider showing a notification when a Flutter developer opens an ARB file offering to install the extension.

Something like:

The ARB Editor extension can help with editing '.arb' files
[Install Extension] [Don't Show Again]

If the user does not interact with the notification at all (because they might not have noticed it and VS Code hides it after ~10s) we could re-show it only after some snooze period.

It should be shown:

• only if the extension is not already installed
• only if we have detected a Dart or Flutter project (Dart doesn't currently use ARB files? @mosuem)

Questions:

• How long should we snooze before showing it again if not interacted with?
• Should we show it some maximum number of times and then give up (eg. if a user keeps ignoring it, perhaps they expect us to stop asking?)

(cc @jacob314 @anderdobo)