This allows to fix some cases when there is a difference between explicit and short reference to default object
Fix shorten reference, optimize imports and import insert helper for default objects
ShortenReferences always transforms default object references to shorter form for now
Fix DescriptorUtils#getFqName() for default objects (affects test data mostly)
Fix DescriptorUtils#getImportableDescriptor()
Basically, this commit splits test data from the from java-txt-kt to two pairs java-txt and kt-txt.
This commit leads to some duplication in test data.
This is temporary: in the platform types branch the test data for LoadJava tests will be changed dramatically, so duplication will go away
Pavel V. Talanov