Fix go to definition to symbols defined in referenced assemblies and have not normalized file paths (#3773)

* fix Solution.TryGetDocumentFromPath for relative paths

* temp logging

* debug

* normalize range.filename in TaskPickle

* remove debug

* Revert "normalize range.filename in TaskPickle"

This reverts commit 31967a5833b566ad3cfb6270d685c0eb012d38f5.

* normalize full paths in mkRange

* remove null check