[#4472]+[#4483] Moved type-name resolution out of Puppet::Parser::TypeLoader.

Moved type-name resolution out of Puppet::Parser::TypeLoader, and into
its primary client, Puppet::Resource::TypeCollection. TypeCollection
now always passes fully qualified type names to TypeLoader.

This avoids duplicate type-name resolution logic between TypeLoader
and TypeCollection. That in turn fixes bug 4472, which resulted
from flaws in the type-name resolution logic in TypeLoader.

In addition, it fixes bug 4483, which resulted from improper
interleaving between looking up names using the TypeCollection and the
TypeLoader.