Type and Signatures are not emitted

These will be needed to reconstruct hovers in lsif-semanticdb. Everything needed is outlined in the semanticdb specs for [Type](https://scalameta.org/docs/semanticdb/specification.html#type-2) and for [Signature (under SymbolInformation)](https://scalameta.org/docs/semanticdb/specification.html#java-symbolinformation).