[lldb][COFF] Match symbols from COFF symbol table to export symbols

If a symbol is the same as an export symbol, mark it as 'Additional' to
prevent the duplicated symbol from being repeated in some commands (e.g.
`disas -n func`). If the RVA is the same but exported with a different
name, only synchronize the symbol types.

Reviewed By: labath

Differential Revision: https://reviews.llvm.org/D134426