Add support for zstandard compressed ESXi boot modules

[Schamper]

ESXi9 started compressing boot modules with zstandard (with a signing footer) instead of LZMA. We should add support for that:

dissect.target/dissect/target/plugins/os/unix/esxi/_os.py

Line 282 in eaa3440

if cfile.peek(6)[:6] == b"\xfd7zXZ\x00":

Related to #1191.