Add restart command for Playwright browser tunnel

[JM (justinTM)]

Adds a small restart command for the Playwright Local Browser Server VS Code extension.

Changes:

• Contributes playwright-local-browser-server.restart.
• Registers a restart handler that stops and then starts the tunnel.
• Adds Restart Tunnel to the status bar quick-pick menu.
• Documents the command in the extension README.

Validation:

• Parsed vscode-extensions/playwright-local-browser-server-vscode-extension/package.json.
• Checked that start/stop/restart command contributions are present.
• Ran git diff --check.

Note:

• Full Rush build was not run on the remote host because the checkout was sparse and Rush required unrelated monorepo project manifests. Initial Rush install also hit /home disk capacity before temp/cache were redirected to /tmp.

[Ian Clanton-Thuon (iclanton)]

JM (@justinTM), can you sign the CLA?

[JM (justinTM)]

Ian Clanton-Thuon (@iclanton) yep! sorry
@microsoft-github-policy-service agree