tnt_pass_http_request: support arrays in query string via parse_args parameter

[VifleY]

Feature request.

Though query string format is not specified in rfc3986 (URI syntax), some of web servers support arrays in query parameters.

For example:
PHP: ?array[]=1&array[]=2 => [1,2]
Some of Node.js and Python frameworks: ?array=1&array=2 => [1,2]

Suggestion: encode such parameters as Lua table passed to TNT via request.args
Ex:
URI: ?array=1&array=[2]
Tarantool:
type(request.args['array']) == 'table'

That would help users to avoid usage of their own format to parse multivalue parameters.