service: add component runstate

service: add component runstate

This commit adds a new flag that the component (or "backend")
can use to indicate readyness. The service function callback
will not be called until the component sets itself as ready.

The use-case behind adding this feature is eg: a service that
requires configuration before it can start. Any service that
emulates an ethdev will have rte_eth_dev_configure() called,
and only after that the service will know how many queues/etc
to allocate. Once that configuration is complete, the service
marks itself as ready using rte_service_component_runstate_set().

This feature request results from prototyping services, and
requiring a flag in each service to note "internal" readyness.
Instead that logic is now lifted to the service library.

The unit tests have been updated to test the component runstate.

Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
Acked-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>