Remove Windows editline from LLDB

I don't mean to undo others' work but it looks like the hand-rolled EditLine for LLDB on Windows isn't used.  It'd be easier to make changes to bring the other platforms' Editline wrapper up to date (e.g. simplifying char vs wchar_t) without modifying/testing this one too.

Reviewed By: amccarth

Differential Revision: https://reviews.llvm.org/D102208