I think with the solution scope, it's better to use `FSharpSymbol.Assembly` property. To be clear:

- Expose `AssemblyName` from IProjectProvider (I think `getProperty "AssemblyName"` should return correct names. If not, we can use ProjectFileName).
- Pass AssemblyName as a project configuration so that `Assembly` is populated in `FSharpSymbol`.
- Check symbols in solution by matching assembly names.