debian: provide fuseext2 to replace src:fuse-umfuse-ext2

debian: provide fuseext2 to replace src:fuse-umfuse-ext2

The fuse-umfuse-ext2 packaghas been abandoned by upstream, and a
follow-up fork at https://github.com/alperakcan/fuse-ext2 hasn't been
updated in five years.  Both of these versions also warn against
mounting file systems read/write with fuse-ext2.

As proposed on debian-devel, let's replace fuse-umfuse-ext2 with a
compatibility shell script shipped with fuse2fs.

Link: https://lists.debian.org/debian-devel/2024/10/msg00231.html
Addresses-Debian-Bug: #1085590
Signed-off-by: Theodore Ts'o <tytso@mit.edu>