VHDL-2008: Generic packages on entity should test all cases

[bpadalino]

The VHDL-2008 test tb_generic_packages_on_entity exposed that most simulators do not handle the cases for passing a generic package into an entity. It's defined as:

interface_package_declaration ::= package identifier is new uninstantiated_package_name interface_package_generic_map_aspect

interface_package_generic_map_aspect ::= generic_map_aspect | generic map (<>) | generic map ( default )

So the test really should be 3 tests:

• Test with a generic_map_aspect (i.e. a normal generic map)
• Test with generic map (<>) (i.e. any mapping)
• Test with default (i.e. only the default package mapping)