Add github scoped creds and jupyterlab favorites

[fperez]

The most important one is the github scoped creds tool, the other is mostly convenience.

@consideRatio - this is so we can more easily push/pull from github with @yuvipanda's scoped creds tool. I tried using it but I'm getting:

So perhaps there's more than installing the package to do?

[consideRatio]

The previous version of the tool with another name was setup here in the dockerfile.

There are two environment variables that need to be set, and they are now configured in a 2i2c-org/infrastructure fork/PR because of needs JMTE has that 2i2c isn't compatible with: https://github.com/2i2c-org/infrastructure/pull/436/commits/5a9f69b11727965fd4f07571c03eb65de5279fa4

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This should work now I think! I cleaned up old logic in #124 to avoid possible conflicts.

[yuvipanda]

Thanks a lot, @consideRatio!