Add Lit as an explicit dependency of video-series-samples

[AndrewJakubowicz]

Context

When using npm install github:lit/video-series-samples, the dependencies are installed from the root package.json.

Why

This is needed to install the simple carousel from Github in the BWL002 video and have the lit dependency resolve. We need the root package.json to depend on the simple-carousel project.

Tradeoffs

This duplicates the Lit dependency in the root package.json which is used to install dependencies during a npm github install. This is a strange case because we want to allow npm install of the repo to use the simple-carousel easily, but we also want the simple carousel folder to be a self contained project that can also be installed.

The root package.json needs enough information to install dependencies and use the built simple-carousel. And the simple carousel folder also needs enough information to install itself as a self contained project (mimics the lit-starter-template structure).

@rictic perfectly resolved the tradeoff by suggesting a file dependency. Tested and it works! Dependencies are now DRY! Thank you!

Testing

Tested manually by using npm link and npm link video-series-samples. Then locally using this in create-react-app which is done in the video.

Commands used in video:

npx create-react-app@latest carousel-in-react

cd carousel-in-react

npm install github:lit/video-series-samples

[AndrewJakubowicz]

@rictic gave offline feedback that instead of trying to duplicate the dependencies manually in the root package.json, a file: dependency is cleaner. It infinitely improved this PR and taught me something new. Thank you!

Requesting review.