Improve WebUI net tab - preserve selected nodes and edges on data reload

[skrashevich]

This commit introduces new features aimed at enhancing the user interaction with network visualizations on a web page. Specifically, the update allows both nodes and edges to be selected within the network visualization tool. The JavaScript code updates involve:

1. Declaring variables to capture the selected nodes and edges using getSelectedNodes() and getSelectedEdges() methods.
2. Updating the network data with these selected nodes and edges using selectNodes() and selectEdges() methods.

[AlexxIT]

Thanks! It's better to check what you write.
Any manipulation with edges doesn't work and resets the node positions.
Saving the selected node works well.

[AlexxIT]

https://github.com/AlexxIT/go2rtc/releases/tag/v1.9.9