feat: add import-test package with initial setup and test for RTCPeerConnection

- Created a new package `import-test` with its own package.json and package-lock.json.
- Added a postinstall script to build the webrtc package after installation.
- Implemented a basic test script that initializes an RTCPeerConnection from the `werift` package.
- Updated the webrtc package.json to include a new dependency `fast-deep-equal`.
- Modified the deploy script in the webrtc package to run tests in the import-test directory after publishing.

Author: shinyoshiaki