fuse: add setlease file operation

fuse: add setlease file operation

Add the setlease file_operation to fuse_file_operations, pointing to
generic_setlease.  A future patch will change the default behavior to
reject lease attempts with -EINVAL when there is no setlease file
operation defined. Add generic_setlease to retain the ability to set
leases on this filesystem.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260112130121.25965-1-jlayton@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>