Gitpod: minor: Do not promote extension if it's already installed

[Kreyren]

Currently gitpod promotes the gitpod extension even if it's already installed which i find annoying -> Suggesting it to not display if extension is already installed

[jankeromnes]

Thanks! I was able to reproduce this.

For some reason in my Firefox Nightly on Mac OS, the Gitpod extension is installed and enabled, but it doesn't seem to do anything (no Gitpod logo in the top right browser bar).

EDIT: The extension actually works on GitHub. Chrome also shows the (active) Gitpod logo. However Gitpod loading screen still shows the extension hint. I guess the extension check is broken.

[gtsiolis]

This is no longer reproducible. I'm only seeing the prompt when I don't have the browser extension installed. Closing this. /cc @Kreyren @jankeromnes

[gtsiolis]

Just run into the prompt a couple of times while having the extension installed. Let's reopen this. @jankeromnes do you know if we no longer check this?