Moved validate_edp from plugin SPI to edp_engine

Now EDP engine is fully responsible on validation of data for
job execution.

Other changes:
* Removed API calls from validation to remove circular dependancy
* Removed plugins patching in validation to allow non-vanilla
  plugins testing
* Renamed job_executor to job_execution

Change-Id: I14c86f33b355cb4317e96a70109d8d72d52d3c00
Closes-Bug: #1357512
Merge "Moved validate_edp from plugin SPI to edp_engine"