I didn't fully configure the new dependencies correctly or fully get
them working with our tooling rigging for compilation databases.
- I needed to fix the sha256 of the benchmark. I pasted the wrong
one, but didn't test it effectively.
- Didn't successfully enable the use of Abseil from GoogleTest
(including nice things like its symbolization, etc). Doing this is
a bit awkward as it needs to go into our `.bazelrc`, but it works.
- Didn't add libraries other that GoogleTest to the compile flags.
- Didn't teach the compilation database creation step to cause these
external repositories to be linked in and populated nicely.
All of these are fixed. As I was making changes to the Python script
here, I've added a test to at least type check it and fixed the type
errors reported.