Support tool event logging for fastboot

This is part of the adte team's effort to collect metrics that help understand the bottlenecks in the Android local testing workflow.

Added a fastboot function in build/envsetup.sh which wraps the actual
fastboot binary with the logging script

Bug: 346363374
Test: source build/envsetup.sh && lunch
aosp_cf_x86_64_phone-trunk_staging-userdebug && fastboot --version
tested in both bash and zsh

Change-Id: Ia8d29b4323b64f9f853ee096728993096d7babe9