fix container inspect output to not escape html chars

The default std json behavior is to escape &, < and >. Because we print
to the terminal we do not want escapes and rather the real chars.

That is what PrintGenericJSON() does but because we have custom
MarshalJSON() overwrite on the type which called json.Marshal() this
option was not carried into that. The inner type must not escape it.

This is not a problem in the other direction because the outer
json.Marshal call will still escape the chars returned from the inner
MarshalJSON() result if needed.

Fixes: #28560

Signed-off-by: Paul Holzinger <pholzing@redhat.com>