Add URI sanitiser

[MuntashirAkon]

Interceptor can be used to sanitise data fields.

[Atrate]

It may also be used to rewrite some URLs to more privacy-respecting sites (e.g. reddit -> teddit.net) like https://framagit.org/tom79/nitterizeme

[MuntashirAkon]

Yeah, I will allow some custom rules. These could be supplied as built-in, I suppose.

[MuntashirAkon]

AM will only allow simple rules. Privacy redirect seems to be a complex feature. So, here's what I'm going to do:

We will create an extension (simply copying the source code from UntrackMe) which will set the redirection rules in AM. This way people can configure the instances, etc. without having to leave the app.

But before that, I need to implement #75 (MIME and Schema based default apps).

[MuntashirAkon]

We shall follow URLChecker and privacy-redirect apps to implement the features.