[Lldb/Lua] Generate Lua Bindings

This patch uses SWIG to generate the Lua bindings for the SB API. It
covers most of the API, but some methods require a type map similar to
Python.

Discussion on the mailing list:
http://lists.llvm.org/pipermail/lldb-dev/2019-December/015812.html

Differential revision: https://reviews.llvm.org/D71235