Write to log file and add --upload-metadata to publish metadata files

[ghengeveld]

Fixes AP-3531, AP-2517

First of all, this updates our logging to write the CLI logs to a chromatic.log file besides printing to the terminal. The log file format is akin to what the logs look like in CI.

Secondly, this adds an option to upload a set of "metadata" files, which will be available as part of the published Storybook in the .chromatic directory. A directory index is provided:

📦 Published PR as canary version: 7.5.0--canary.836.6619467092.0

✨ Test out this PR locally via:

npm install [email protected]
# or 
yarn add [email protected]

[tevanoff]

Love this, this is great! However, you say:

these files will be public on a public Storybook.

That sounds like a deal breaker to me. Can we sync up on options for storing these more securely?

[ghengeveld]

@tevanoff I opened a PR for the CDN to not allow public (non-member) access to these files.

[tmeasday]

@ghengeveld perhaps change the PR description as this could unduly worry someone who reads this PR.

[tmeasday]

LGTM, good stuff