Switching from fuse2 to fuse3 in main

[Graham Inggs]

Fuse3 is a requirement for qemu 6 [1]. Since we don't want to support
two versions of fuse in main, we'd like reverse-dependencies of fuse
to switch to fuse3.

A test rebuild of packages in main with a build-dependency on
libfuse-dev was done, switching the build-dependency to libfuse3-dev.

The following packages do not require changes at this time:

* ceph is compatible with fuse2 and fuse3
* gvfs is compatible with fuse3, and carries a patch reverting to fuse2

* e2fsprogs builds fuse2fs, which is in universe
* libvirt builds libvirt-daemon-driver-lxc, which is universe
* ntfs-3g builds with an internal libfuse-lite

Bugs have been filed for the following packages that need to be
adapted to build with fuse3:

* grub2 / grub2-unsigned [2]
* open-vm-tools [3]
* s390-tools [4]
* snapd [5]
* xdg-desktop-portal [6]

Please talk to upstreams and investigate what changes are required to
these packages, but please don't upload until all of the other
affected packages are ready.
Some references: fuse 3.0.0 changelog [7], changes made to ceph [8],
gvfs [9] and grub2 in OpenMandriva [10].


[1] https://bugs.launchpad.net/ubuntu/+source/fuse3/+bug/1934510
[2] https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1935659
[3] https://bugs.launchpad.net/ubuntu/+source/open-vm-tools/+bug/1935665
[4] https://bugs.launchpad.net/ubuntu/+source/s390-tools/+bug/1935666
[5] https://bugs.launchpad.net/ubuntu/+source/snapd/+bug/1935667
[6] https://bugs.launchpad.net/ubuntu/+source/xdg-desktop-portal/+bug/1935668
[7] https://github.com/libfuse/libfuse/blob/master/ChangeLog.rst#libfuse-300-2016-12-08
[8] https://github.com/ceph/ceph/commit/cb0a600acfca76c5b4653e4c6f34c1712a2da9de
[9] https://gitlab.gnome.org/GNOME/gvfs/-/commit/7a0a06186b6fef07b8fce2360c04fd075fc84ed1
[10] https://github.com/OpenMandrivaAssociation/grub2/blob/master/grub-2.02-fuse3.patch