Query build system of workspaces to determine best workspace to open a file in

This sets the stage for multi-workspace support. Everything should be handled internally, we are just missing the API to actually open multiple workspaces at this point.

Sources/SKCore/CompilationDatabaseBuildSystem.swift

@@ -187,6 +187,19 @@ extension CompilationDatabaseBuildSystem: BuildSystem {
       }
     }
   }
+
+  public func fileHandlingCapability(for uri: DocumentURI) -> FileHandlingCapability {
+    guard let fileUrl = uri.fileURL else {
+      return .unhandled
+    }
+    return queue.sync {
+      if database(for: fileUrl) != nil {
+        return .handled
+      } else {
+        return .unhandled
+      }
+    }
+  }
 }
 
 extension CompilationDatabaseBuildSystem {