Add debug logging of requirements
Description
This should resolves #285 (closed) by allowing the debug logging to show the requirement jobs require and the capablities that workers advertise.
Validation
Logs now include lines like
2020-05-13 22:16:56,022:[ buildgrid.server.scheduler][DEBUG][gRPC_Executor_0]: Job created for action [af695567]: [ec911fb1-71f2-4d3e-848f-93fd72e382f6 requiring: {'ISA': ['x86-64'], 'OSFamily': ['linux']}]
and
2020-05-13 22:17:04,400:[ buildgrid.server.bots.instance][DEBUG][gRPC_Executor_0]: New Workers Capabilities: {'OSFamily': {'linux'}, 'ISA': {'x86-64'}}
I dont now if this is going to add too much too the logs, I have tried to add these as sparingly as possible while being enough to debug.
Edited by Points Waves