treewide: Change URLs to HTTPS

Lots of URLs were HTTP redirect to HTTPS. Changed those and checked them
if there's actual content. Inspired by
https://github.com/NixOS/nixpkgs/issues/60004

pkgs/applications/science/misc/openmvg/default.nix

@@ -42,7 +42,7 @@ stdenv.mkDerivation rec {
 
   meta = {
     description = "A library for computer-vision scientists and targeted for the Multiple View Geometry community";
-    homepage = http://openmvg.readthedocs.io/en/latest/;
+    homepage = https://openmvg.readthedocs.io/en/latest/;
     license = stdenv.lib.licenses.mpl20;
     platforms = stdenv.lib.platforms.linux;
     maintainers = with stdenv.lib.maintainers; [ mdaiter ];