Merge branch 'feature/logging' into 'master'

Add logging library

Logging library, intended to be used across other components.
Uses design similar to Android NDK logging APIs and allows for both compile time and run time filters, similar to logcat.

Also includes cleanup of cpu_startup.c — i was changing some logging output in this file so decided to re-format it and reduce code duplication.

Ref TW6703

See merge request !68