JSONSchema: add support for array parameter in api calls, cli and config

JSONSchema: add support for array parameter in api calls, cli and config

a few things were missing for it to work:
* on the cli, we have to get the option as an array if the type is an
  array
* the untainting must be done recursively, otherwise, the regex matching
  converts an array hash into the string 'ARRAY(0x123412341234)'
* JSONSchema::parse_config did not handle array formats specially, but
  we want to allow to specify them multiple time
* the biggest point: in the RESTHandler, to be compatible with the
  current gui behavior, we have to rewrite two parameter types:
  - when the api defines a '-list' format for a string type, but we get
    a list (because of the changes in http-server), we join the list
    with a comma into a string
  - when the api defines an 'array' type, but we get a scalar value,
    wrap the value in an array (because for www-form-urlencoded, you
    cannot send an array with a single value) add tests for this
    behavior, some of which we want to deprecate and remove in the
    future

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>