Charts should be interactive

[GyulyVGC]

Sniffnet has always displayed a line-series chart for incoming/outgoing traffic intensity in the Overview page of the app.
Said chart has various limitations: among the most notable ones, users cannot interact at all with it.
The same limitation also hold for the donut chart reporting agglomerated statistics (introduced in version 1.4.0).

Charts should instead be interactive to convey additional information:

• hovering on each segment of the donut chart should display the relative amount of data
• hovering on each data point of the line-series chart should display the relative amount of data AND the involved items in that specific point in time (network hosts, services, notifications if any, etc.)

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Note

Currently the line-series chart is rendered using plotters-iced which is mostly unmaintained and doesn't properly support hover events.
This means that we'll have to create a custom Iced widget for this feature.