Add Wasp SDK to npm Workspaces

[cprecioso]

Based on #3159

The Wasp SDK is not currently added as a workspace to the user project.

If we did it, we could remove the specific npm install step from the SDK, and have even stronger dependency sharing.

The blocker is #2482, because when npm resolves the dependencies there's one deep in the tree that asks for @types/react@19 and we only have @types/react@18, so it errors out.

[infomiho]

I believe that we can remove one specific @prisma/client hack after we implement this: #3479