Add an option to "Add existing file" to a project

[MangelMaxime]

Currently we can only add new file to the project:

It would be nice to also have the possibility to add an existing file

I see to way of doing it:

1. Compute on VSCode side the relative path to add and use the existing fsproj/addFile command
2. Add a new command to FSAC called fsproj/addExistingFile and do all the logic on FSAC side

Would you be ok to add this feature? Which solution would you prefer to use?

[Krzysztof-Cieslak]

Sounds good to me, and I'd rather have logic on FSAC side.