Allow to deprecate extensions

[amvanbaren]

@ModyQyW asked in eclipse/openvsx#603: "Hi. I wonder is there a way to deprecate extensions?"

[kineticsquid]

@amvanbaren @ModyQyW Good question. What's the desired end result? Is it to have an extension removed entirely, versions removed, or perhaps some kind of deprecated status tag attached to the extension?

[ModyQyW]

I think adding a deprecated status to the extension and recommending a alternative if possible will be better.

Actually, the idea comes from microsoft/vscode-discussions#1.

[kineticsquid]

First step is taking ownership of a list of deprecated and malicious extensions: #1938.