feat: Improve support for unprivileged hosts (including LXC) (#479)

* * Add fakeroot to extract the dsm system without elevated permissions
* Remove obsolete docker variable "DEV" used to exclude extraction of device nodes

* feat: Detect unprivileged container

* fix: Use fakeroot for mke2fs

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Co-authored-by: Kroese <kroese@users.noreply.github.com>

Dockerfile

@@ -29,6 +29,7 @@ RUN apt-get update && apt-get -y upgrade \
         iptables \
         iproute2 \
         dnsmasq \
+        fakeroot \        
         net-tools \
         qemu-utils \
         ca-certificates \