Rename "Tor Browser" into "Tor Downloads"

As suggested by huertanix in #15028.

We have very little data on whether “Tor Browser” and “Tor Browser (persistent)” work for people, so we might as well try to change it and see how it goes.

The code for that living in config/chroot_local-includes/usr/local/lib/add-GNOME-bookmarks.

We should also quickly check our doc for references and screenshots. At least /doc/anonymous_internet/Tor_Browser needs updating.

Related issues

Is duplicate of #15028

Original created by @sajolida on 15464 (Redmine)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information