This deprecates --vmodule (not available in absl, mapping it to --v for
a very minimal sort of compatibility) and adds the absl::log flags
--minloglevel, --stderrthreshold, --log_backtrace_at, and --log_prefix.
Reorder headers to follow the Google C++ Style Guide:
> In dir/foo.cc or dir/foo_test.cc:
>
> 1. dir2/foo2.h.
> 2. A blank line
> 3. C system headers (more precisely: headers in angle brackets with
the .h extension), e.g., <unistd.h>, <stdlib.h>.
> 4. A blank line
> 5. C++ standard library headers (without file extension), e.g.,
<algorithm>, <cstddef>.
> 6. A blank line
> 7. Other libraries' .h files.
> 8. A blank line
> 9. Your project's .h files.
https://google.github.io/styleguide/cppguide.html#Names_and_Order_of_Includes
This feeds into efforts to create a working install target.
The order of headers is still funky, and was "fixed" by clang-format,
but in a way that doesn't exactly align with the style guide. Further
cleanup of header order is coming in a follow-up PR.
Related to issue #1047
After this it should be possible to build a working `packager` application from the `cmake` branch. Some further logging improvements may be needed to get full parity with the `main` branch in terms of ability to do verbose debug logging, but other than that everything is expected to work.