Tipping support for privacy front-ends

Putting an issue in to track this, we would like to add tipping support for some privacy front-end alternatives like Nitter for example.

Here is a list of some: https://libredirect.github.io/

Start by reviewing the privacy-front-end list at https://libredirect.github.io/ and define which alternatives and tipping flows are in scope. Done should mean that the selected front-ends support tipping through the extension, with the supported list and expected behavior documented.

Written by the indexing model from the issue text.