Outside user able to request access to Node

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Feature Description

We should allow outside users to request access to a Node.

Create a "sign up" screen which would generate a registration request to PyGrid.

All new users requests would be shown in the /Users tab. They'd be approved or denied.

@IonesioJunior this is one of the new tables we talked about.

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@IonesioJunior is this in your future workflow?