Remove UIService

This class seems to have been introduced at some point to reduce the
dependency on VS Code from the test UI service. However, none of its
methods are being used anymore, and by using typed commands we have
already reduced the dependency on VS Code. Therefore, we can simply
remove this class.

Author: koesie10

extensions/ql-vscode/src/test-ui.ts

@@ -14,7 +14,6 @@ import {
 import { showAndLogWarningMessage } from "./helpers";
 import { TestTreeNode } from "./test-tree-node";
 import { DisposableObject } from "./pure/disposable-object";
-import { UIService } from "./vscode-utils/ui-service";
 import { QLTestAdapter, getExpectedFile, getActualFile } from "./test-adapter";
 import { TestUICommands } from "./common/commands";
 
@@ -42,7 +41,7 @@ class QLTestListener extends DisposableObject {
 /**
  * Service that implements all UI and commands for QL tests.
  */
-export class TestUIService extends UIService implements TestController {
+export class TestUIService extends DisposableObject implements TestController {
   private readonly listeners: Map<TestAdapter, QLTestListener> = new Map();
 
   constructor(private readonly testHub: TestHub) {