test(appcomposer): fix initMessageHandler flaky test. (#5973)

## Problem
See issue: #5970

## Solution
appears to be similar to
#5955, so same solution is
employed.
- skip test if below 1.89 vscode version. 
- add helper function `skipIfVscodeBelow` for tests that are flaky on
previous versions.

---

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License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

Author: Hweinstock

packages/core/src/shared/vscode/env.ts

@@ -67,10 +67,10 @@ export { extensionVersion }
  *
  * @param throwWhen Throw if minimum vscode is equal or later than this version.
  */
-export function isMinVscode(throwWhen?: string): boolean {
+export function isMinVscode(options?: { throwWhen: string }): boolean {
     const minVscode = getMinVscodeVersion()
-    if (throwWhen && semver.gte(minVscode, throwWhen)) {
-        throw Error(`Min vscode ${minVscode} >= ${throwWhen}. Delete or update the code that called this.`)
+    if (options?.throwWhen && semver.gte(minVscode, options.throwWhen)) {
+        throw Error(`Min vscode ${minVscode} >= ${options.throwWhen}. Delete or update the code that called this.`)
     }
     return vscode.version.startsWith(getMinVscodeVersion())
 }

packages/core/src/test/applicationcomposer/messageHandlers/generateResourceHandler.test.ts

@@ -8,11 +8,11 @@ import sinon from 'sinon'
 import { createTemplate, createWebviewContext } from '../utils'
 import { generateResourceHandler } from '../../../applicationcomposer/messageHandlers/generateResourceHandler'
 import { Command, MessageType } from '../../../applicationcomposer/types'
-import * as env from '../../../shared/vscode/env'
+import { isMinVscode } from '../../../shared/vscode/env'
 
 describe('generateResourceHandler', function () {
     it('amazon q is not installed', async function () {
-        if (env.isMinVscode('1.89.0')) {
+        if (isMinVscode({ throwWhen: '1.89.0' })) {
             this.skip()
         }
         const panel = await createTemplate()

packages/core/src/test/applicationcomposer/messageHandlers/initMessageHandler.test.ts

@@ -7,13 +7,17 @@ import assert from 'assert'
 import sinon from 'sinon'
 import { initMessageHandler } from '../../../applicationcomposer/messageHandlers/initMessageHandler'
 import { createTemplate, createWebviewContext } from '../utils'
+import { isMinVscode } from '../../../shared/vscode/env'
 
 describe('initMessageHandler', function () {
-    afterEach(() => {
+    afterEach(function () {
         sinon.restore()
     })
 
-    it('not connected to codewhisperer', async () => {
+    it('not connected to codewhisperer', async function () {
+        if (isMinVscode({ throwWhen: '1.89.0' })) {
+            this.skip()
+        }
         const panel = await createTemplate()
         const postMessageSpy = sinon.spy(panel.webview, 'postMessage')
         const context = await createWebviewContext({