Improve test coverage for Strv.from
Fix test description
Remove unused method MappingMethodBuilder.for_signal
Remove unused method ReceiverArgumentInfo#skip?
Use memoized type size when looping over elements
Remove obsolete and incorrect skip guards

The failure of these tests was causes by the incorrect marshalling
functions declared in the Regress library. Due to the use of closures
with their own generated marshalling, these marshalling functions are
now ignored and the tests pass.
Create helper class Foo
Move parameter_preparation to Foo
Creation return value builders in factory methods
Move return_value_conversion to Foo
Move #capture_variable_names to Foo
Move #call_arguments to Foo.call_argument_names
Remove unused vargen initializer argument
Move creation of argument name list to Foo
Move return value name logic to Foo
Remove unused initializer arguments
Simplify signature of Foo.set_up_argument_relations
Remove unused initializer argument 'vargen'
Move setting up argument relations into Foo
Rename Foo to ArgumentBuilderCollection