Add Tor Browser-specific licenses in about:license
This idea came out of #33771 (moved) and #33772 (moved). GeKo mentioned that we don't need to ship a specific license for NSS because it is covered by about:license, and we could use about:license for the additional licenses we must ship, as well. Currently those Tor Browser-specific licenses are controlled by tor-browser-build and they are included as text files at build-time. Extending about:license is a good idea.
The main disadvantage I see is downstream projects who take a tor browser package and re-use all of the tor parts but they don't use the browser. We could achieve this by continuing with adding licenses in text files and then patching them into tor-browser's toolkit/content/license.html at build time. I'm not very excited about the additional complexity this would require, though.