Add support for building the CEF binary distribution using Bazel
and the default platform toolchain. Tested to work for Windows
x64, MacOS ARM64 and x64 (cross-compile from ARM64), and
Linux x64. Windows x86 (cross-compile from x64) is known to
be broken, see https://github.com/bazelbuild/bazel/issues/22164.
Includes minor changes to tests directory structure to meet
Bazel build requirements.
