Feature Request: Different `vscode:prepublish` for pre-release extensions

[Danielku15]

I'd like to run different scripts on whether I'm packaging a pre-release or release version of my extension but there is no information available about this flag in the scripts.

It would be great if there is vsce can call different scripts for pre-release or release package and publish commands.

Currently I need to handle this separately by calling some scripts manually.

[benibenj]

@Danielku15 would having a vscode:prepublish:prerelease and vscode:prepublish:release script help?

Packaging an extension would run the pre publish script vscode:prepublish followed by either vscode:prepublish:release or vscode:prepublish:prerelease depending if it is pre release or not.

(Will also require updating the docs here and here)