Implement censorship monitoring via OONI

We are now effectively victim of state censorship in Russia.

We have discovered it because users started to complain seriously.

We needed to run a few investigation to confirm this. See https://github.com/kiwix/operations/issues/656 for more information.

We could maybe use OONI to be informed earlier and in a rigourous manner about when, where and how our services get censored.