adb: switch skip_host_serial to string_view.

Rename it to something more appropriate, while we're at it.

Test: test_adb.py
Test: test_device.py
Test: $ANDROID_HOST_OUT/nativetest64/adb_test/adb_test
Test: adb shell /data/nativetest64/adbd_test/adbd_test
Change-Id: I0f95d348eeacb45a810696d748c8340d2068f666