send uris for git.mergeChanges context as objects (#160390)

That way they undergo uri transformation and the setContext-command will stringify them so that everything works, fixes #159837

extensions/git/src/repository.ts

@@ -2081,7 +2081,7 @@ export class Repository implements Disposable {
 		this.setCountBadge();
 
 		// set mergeChanges context
-		commands.executeCommand('setContext', 'git.mergeChanges', merge.map(item => item.resourceUri.toString()));
+		commands.executeCommand('setContext', 'git.mergeChanges', merge.map(item => item.resourceUri));
 
 		this._onDidChangeStatus.fire();