Use Plack::Request as the query object

[bschmalhofer]

In rel-10_1 most stuff is converted to Plack. But Kernel::System::Web::Request still uses a CGI.pm compatible object internally. It would be nice to convert that `$Self->{Query} to a Plack::Request object. But I'm not sure whether it is worth the effort.
At least two hurdles must be taken in stride:

• Plack::Request::param() can't be used to set values, see Turn Kernel::System::Web::Request into a immutable class #825
• some scripts, maybe exclusively test scripts, pass a CGI.pm object to the constructor of K::S::W::Request.

Making the switch would also allow the remove Kernel/cpan-lib/CGI .

[bschmalhofer]

This has been implemented for OTOBO 11.0. See #1683.