fix: best-effort support for POMs when highlighting

[mxschmitt]

Fixes microsoft/playwright#27036

Adding a test was more involved than I thought. We already have some logic in place to connect to an existing "ReusableBrowser" but the issue is that waitForPage calls _newContextForReuse which will reset it, and I want to keep the old content.

playwright-vscode/tests/utils.ts

Lines 71 to 87 in ba3258a

	export async function connectToSharedBrowser(vscode: VSCode) {
	await expect.poll(() => vscode.extensions[0].browserServerWSForTest()).toBeTruthy();
	const wsEndpoint = vscode.extensions[0].browserServerWSForTest();
	return await chromium.connect(wsEndpoint, {
	headers: { 'x-playwright-reuse-context': '1' }
	});
	}
	export async function waitForPage(browser: Browser) {
	let pages: Page[] = [];
	await expect.poll(async () => {
	const context = await (browser as any)._newContextForReuse();
	pages = context.pages();
	return pages.length;
	}).toBeTruthy();
	return pages[0];
	}

I went a different route over CDP instead.

[dgozman]

Let's add a test for this.

[mxschmitt]

note: reason for moving it out was that the tests were not isolated before, the _debugSession struct leaked.