(PUP-488) Add specs fur future Resource parameter/metaparameter access

This is just adding a little additional spec coverage for the future
parser Resource[foo][attribute] syntax where attribute is either a
parameter or a metaparameter.  It also checks some
virtual/realized/exported variations.

From debugging, it appears that the only values being accessed during
evaluation are those either set directly on the Puppet::Parser::Resource
instance's Puppet::Parser::Resource::Params, or the default
Puppet::Parser::Resource::Params which have been set in the current or
parent scopes during evaluation of a
Puppet::Pops::Model::ResourceDefaultsExpression for the given resource
type.  No attempt is made to lookup the type class's defined parameter
defaults.