bazel branch: work-in progress update

[Otto van der Schaaf <os...@apache.org>]

Hi all,

I wanted to share an update on some of the work we are doing over at the
bazel branch. Our goal there is to move the build system from gyp to bazel,
and make a few improvements and dependency updates along the way (which
became a lot easier on the bazel branch!). When we're done we are well
positioned to modernize the code-base some more (next to the updated string
handling), as well as lean up by shedding more dependencies.

High level, the current status is that the bazel branch compiles with
clang-8 and roughly carves a path to where we want to be, but lots of
details yet need to be resolved. Consensus during discussion on Slack is
that landing some large but mechanical changes on master in preparation
would be useful to ease the transit, as that would help make
reviewing/landing the payload manageable.

the following doc summarizes status quo:
https://docs.google.com/document/d/1_sTwZ2AN8aBpP-tfSbdSLzovchXDCFYTQkD92vb71jQ/edit?usp=sharing

Otto