Create and use extractapi::RecordLocation instead of conventional
clang::PresumedLoc to track the location of an APIRecord, this reduces
the dependency of APISet on SourceManager and would help if someone
wants to create APISet from JSON Serialized SymbolGraph.
These changes also add extractapi::CommentLine which is similar to
RawComment::CommentLine but use RecordLocation instead of PresumedLoc.