[Feature] Handle packager port setting changes in status bar

[ConnorQi01]

Summary

Handle react-native.packager.port setting changes without requiring users to restart VS Code and without showing a configuration-change popup.

When the packager is stopped, the extension should refresh the cached port silently. When the packager is already running, the running port should stay unchanged and the status bar should explain that the new port setting will be applied on the next start.

Proposed Changes

• Listen for VS Code configuration changes during extension activation.
• React only to react-native.packager.port changes.
• Refresh cached packager ports immediately when packagers are stopped.
• Keep active packagers on their current running port.
• Mark the packager status bar item with a warning indicator when a different port is pending.
• Show tooltip text such as:
  • Running on port 8081.
  • Port setting changed to 9090. It will be reset on next start.

Test Plan

• Run npm run build.
• Verify the behavior manually with the packager stopped and running.
• Review the separate stacked test PR for automated test coverage.