make network form persist across tabs

[alexmanuele]

Description

There is a form on the network visualization tab that controls the behaviour of all plots. This allows users to select nodes from the data and indicate threshold values on the distance matrices that relate those nodes, generating a network from the connected components focal to the selected nodes. The distance matrix and clustergram plots are subsequently reduced to only contain nodes that remain in the filtered graph.

The form should be persisted to exist on all tabs of the webpage, and "follow" the user. This is because the form controls the behaviour of all plots.

The function to create the form is currently found in layouts/network_layout.py . Some components of the form are statically defined, and some are dynamically defined by the make_network_form() method.

Acceptance Criteria

• The form to select nodes and thresholds can be seen on all tabs of the app
• The form data is not lost when changing tabs