Allow to deprecate extensions

[amvanbaren]

@ModyQyW asked in https://github.com/eclipse/openvsx/issues/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 https://github.com/microsoft/vscode-discussions/discussions/1.

[kineticsquid]

First step is taking ownership of a list of deprecated and malicious extensions: https://github.com/EclipseFdn/open-vsx.org/issues/1938.

[amvanbaren]

@ModyQyW Support for deprecated extensions has been added, e.g. https://open-vsx.org/extension/ZixuanChen/vitest-explorer. The top section is grayed out and an alternative extension is recommended: "Use vitest instead".