Move RecommendedTBBVersions from check.torproject.org to www.torproject.org

Right now the only reliable way to programatically check for the latest version of TBB is by loading https://check.torproject.org/RecommendedTBBVersions. It would be very helpful if that file could also be hosted somewhere at https://www.torproject.org/. The main Tor Project website has a .onion address, and there are also several mirrors of it. This isn't true of check.torproject.org.

I'm working on Tor Browser Launcher, a program that helps you download, verify signatures, and keep up-to-date TBB: https://github.com/micahflee/torbrowser-launcher

I'm building the option to download updates over Tor, and I'm planning on making a second option to download updates from torproject.org's hidden service: https://github.com/micahflee/torbrowser-launcher/issues/41

The way it stands, the RecommendedTBBVersions request would have to not use the .onion.

I also just made it so you can choose your torproject.org mirror, so you can download the TBB files from a different website: https://github.com/micahflee/torbrowser-launcher/issues/32

If *.torproject.org is getting blocked, you should be able to choose a different mirror from the dropdown in TBL settings and download TBB, as long as the mirror you choose isn't also getting blocked. But there's no way for TBL to ask a mirror what the recommended TBB version is, so even with using mirrors there needs to be a request to check.torproject.org first, which would get blocked and prevent people from using TBB at all.