Creating component interface to improve class heirachy in the test framework

The stress testing framework is growing and as such we're introducing new components, these are:

• Runtime monitor
• Workload generation
• Timestamp engine
• Checkpointer

I'd like to create a standard interface for control over a component. Each one should define a load() and a run() phase. Which can then be called from the test_harness::test class.

Its not clear yet whether the validation or workload tracking components will extend this type.