`Start MakeCode Simulator` command should only appear in editor context menu if in a MakeCode project

[joyceerhl]

1. Install MakeCode extension
2. Open microsoft/vscode repo
3. Open a TS file and right click to open context menu
4. 🐛 see Start MakeCode Simulator in context menu

I would also suggest putting this command in a different group as currently it is grouped with unrelated go to definition actions. If there's only one MakeCode command it may make sense to group it with the other run/debug actions in the debug group, otherwise it could go into a dedicated MakeCode group.

[jwunderl]

Thanks for the suggestion! I added these changes into #150