Basic JWT-based authentication and authorization

[grtlr]

What

This adds a new re_auth crate with the following features:

• JWT-based symmetric authorization and authentication (basic read/write modes).
• Rerun-ified abstraction over jwt-simple so that we can swap it out.
• Helpers to convert a SecretKey from/to base64 to be used with redap-cli.
• tonic::Interceptors for both client and server side middleware with an authorization: Bearer <token> header.

Here is what a SecretKey (HS256) looks like in base64:

pBiQ9NVDj1elVjATgyL5EYri/9paHwvz78lsx7QCq9E=

We can use that to generate a basic token:

eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJyZWRhcC1jbGkiLCJzdWIiOiJqb2NoZW5AcmVydW4uaW8iLCJhdWQiOiJyZWRhcCIsImV4cCI6MTczNjg3MjUzNCwiaWF0IjoxNzM2ODQ0NTM0fQ.QHI99cXIi4VjhZKBJmLb13NynOjvmUWuxy63CUwiBlA

Which you can verify yourself via www.jwt.io.

[github-actions]

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Result	Commit	Link	Manifest
✅	0a01c19	https://rerun.io/viewer/pr/8627	+nightly +main

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[zehiko]

I don't have all the context on what was discussed, but this is really easy to follow code and having a notion of "provider" that can later be switched with some other components makes sense to me.

[grtlr]

@jleibs it would be awesome if you could also have another look. 🙏