[llvm] [Debuginfo] Add llvm-debuginfod-find tool and end-to-end-tests.

This implements the `llvm-debuginfod-find` tool, which wraps the Debuginfod library (D112758) to query debuginfod servers for artifacts according to the [[ https://www.mankier.com/8/debuginfod#Webapi | specification ]].

Reviewed By: labath

Differential Revision: https://reviews.llvm.org/D112759