PSA: crosvm's command-line parameters including '[' and ']' need to be quoted

[Alex Courbot]

crrev.com/c/3915038 adds '[' and ']' as separators for command-line
arguments parsed by serde_keyvalue. This means that if your invocation
of crosvm contained an argument like this:

--my-arg blah[10]

then the argument parsing will fail unless the string is quoted:

--my-arg "blah[10]"

The reason for this is that tuples/struct enums can now be
deserialized from the command-line, with '[' and ']' acting as
delimiters for the tuple/enum.

I suspect nobody downstream will be affected by this change, but
sending this heads-up just in case since I cannot check them all.

Cheers,
Alex.