Add support for AnyWidget

[jourdain]

Having trame to work seamlessly in Jupyter is key for its future and adoption.

We currently support:

• Jupyter Hub proxy infrastructure. (has disconnection issue due to proxy implementation)
• Jupyter Lab extension to handle network communication. This require custom installation which can be an issue.

Ideally AnyWidget could remove custom install needs, while using Jupyter network infrastructure.

Task:

• Implement network communication using AnyWidget infrastructure.
• Expose main trame packages so they can be served from a permanent server. (github.io)