Enable users to enable/disable various data sources in the Internet Outage charts

[agrabeli]

A community member reported that it would be really nice if the Internet Outage charts on OONI Explorer (https://ooni.org/post/2023-new-explorer-features/#charts-on-internet-outages) enabled users to select which of the data sources (Cloudflare, Active Probing, etc.) were displayed.

In other words, it would be great if users, for example, could click Cloudflare, and the chart would only display that.

From an implementation perspective, this would be similar to how if users click middleboxes (or any test group) in the Measurement Coverage charts in each Country page (e.g. https://explorer.ooni.org/country/IT) the relevant data gets enabled/disabled.

[Gaurav-3D2Y-Lakwal]

@majakomel I would to work in this. Can you assign this issue to me (i already make changes on my local and attaching some screenshots



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