LookupConfig - lookup ilm config and override with valid environment settings if any.

EnvILMExpirationWorkers env variable to configure number of expiration workers.

EnvILMTransitionWorkers env variable to configure number of transition workers.

DefaultKVS default configuration values for ILM subsystem.

HelpILM holds configuration keys and their default values for the ILM subsystem.

Config represents the different configuration values for ILM subsystem.