Add workspace attribute for Project Setting

[eleanorjboyd]

Update project setting to have an attribute for "workspace". This will fix the bug where if a multiroot workspaces with the same folder names has one of those folders added, all the others get added too.

demo:
here I add one project to one workspace but since I have a folder named "src" in all my workspaces it adds once per workspace for a total of 3
https://github.com/user-attachments/assets/35614639-e509-4d56-9d0e-da604c898249

this in the settings:

leads to this in the UI:

instead of only showing workspace3/src as the only non-root project since that was the only one selected (see video, video creates attached img of settings)

[eleanorjboyd]

this repo can be found here: https://github.com/eleanorjboyd/python-envs-scenarios

[eleanorjboyd]

To verify (must have python envs extension installed, not installed by default)

• try with this repo:  https://github.com/eleanorjboyd/python-envs-scenarios
• open it as a multiroot workspace
• create a new folder in one of the workspaces
• go to python projects view (python icon in the sidebar)
• new project (folder with plus icon) -> select existing then the folder you just created
• open settings.json
• verify you now see a "workspace" attribute saved in the project json