Workaround VSCode bug where ${script} var not expanded (#1095)

This happens when you start a debug session from a git diff window.

Author: rkeithhill

src/features/DebugSession.ts

@@ -121,9 +121,17 @@ export class DebugSessionFeature implements IFeature, DebugConfigurationProvider
                         vscode.window.showErrorMessage(msg);
                         return;
                     }
+
+                    if (config.script === "${file}") {
+                        config.script = currentDocument.fileName;
+                    }
                 }
             }
 
+            if (config.cwd === "${file}") {
+                config.cwd = currentDocument.fileName;
+            }
+
             if (config.createTemporaryIntegratedConsole !== undefined) {
                 createNewIntegratedConsole = config.createTemporaryIntegratedConsole;
             }