[pidcat] Display package:process_name in process birth/death messages

Summary: Making sense of a birth/death message is made easier by specifying which process it applies to, and not just the component or the pid.

Test Plan: Run, monitor message lines when cycling a multi-process app, inject None as a process name to check resilience.
Merge pull request #50 from LouisBVL/process_output

Display package:process_name in process birth/death messages