Support workspace extensions

[nioufe]

It would be interesting for people working on different projects to have a way to :
1: Set up extensions for the all team to have an uniform configuration
2: Have different extensions on different projects

I think that having a list of extensions in the Workspace configuration could solve this.
Otherwise i'll just have to write an extension for it :-)

[egamma]

Good suggestions, we had discussions along these lines and this falls into the category of how to deal with many extensions and how to work with extensions in a team. This topic is on our 6 month roadmap.

[Thaina]

Thanks @joaomoreno for report duplication

I would like to suggest that VSCode should just look at .vscode/extensions folder of the opened folder to read extension in addition to global .vscode/extensions

[Telokis]

Over one year later, can we have some light on the current status of this issue?