Feature request: Support offset for rdsquashfs

[probonopd]

Feature request: Support offset for rdsquashfs, like unsquashfs does:

[-o BYTES, -offset BYTES]
skip BYTES at start of FILESYSTEM. Optionally a suffix of K, M or G can be given
to specify Kbytes, Mbytes or Gbytes respectively (default 0 bytes).

https://manpages.debian.org/testing/squashfs-tools/unsquashfs.1.en.html#o

[deliciouslytyped]

I ran into a case where a squashfs image is embedded in another file, and this would be useful.