Install-VSCode doesn't support "Stable-User" BuildEdition

[JMGEHMAN]

The BuildEdition parameter of the Install-VSCode.ps1 script should support the "Stable-User" option - it currently only allows "Stable", which results in an install of "Stable-System.

If a user wants to install the Insiders version of VS Code, they have the option of specifying "Insider-System" or "Insider-User". However, there is only one option if selecting the "Stable" version.

Proposed technical implementation details (optional)
Add "Stable-User" to the ValidateSet check for the BuildEdition parameter. With the necessary changes to code to support the additional option. This creates an inconsistency between naming conventions for Stable and Insider editions - not sure what, if anything, should be done to address.

• Option 1
  Keep "Stable" and simply add "Stable-User".

[parameter()]
[ValidateSet("Stable", "Stable-User", "Insider-System", "Insider-User")]
[string]$BuildEdition = "Stable",

• Option 2
  Rename "Stable" to "Stable-System" in addition to adding "Stable-User".

[parameter()]
[ValidateSet("Stable-System", "Stable-User", "Insider-System", "Insider-User")]
[string]$BuildEdition = "Stable-System",

[ghvanderweg]

The ValidateSet used to be just Stable and Insider, and was changed to Stable, Insider-System and Insider-User when that functionality became available for VS Code Insider. So Option 2 would be the way to go in my opinion.

I'd like to pick this up :)

[JMGEHMAN]

Thanks, ghvanderweg. I'd like to take as well. Planning on using it as a demo on contributing to PowerShell/open source.

[ghvanderweg]

Alright, it's all yours then 😀

[TylerLeonhardt]

Awesome!

[corbob]

@TylerLeonhardt if @JMGEHMAN is picking this one up, should the Up-for-Grabs label be removed?

[TylerLeonhardt]

I'll leave the tag for tracking but I did just assign it to @JMGEHMAN and we can use that for ownership.

[JMGEHMAN]

It took too long for me to get approval. Thanks to @Lothindir for fixing.