Switch netd_defaults to C++17

Additionally:
    - use netd_defaults everywhere (except libbpf)
    - a few clang-format and clang-tidy inspired fixes
    - runtests.sh now tries to run "adb root"
    - runtests.sh now can be used to run the benchmarks

Test: as follows
    - built, flashed, booted
    - system/netd/tests/runtests.sh passes

Change-Id: Ifbfada63cf4e541c55f51396f618fff389d664a5