AthenaExamples: cmake configuration and package cleanup

Some housekeeping for the packages under Control/AthenaExamples

• remove atlas_depends_on_subdirs cmake statements
• update link dependencies
• enable flake8 checking where relevant
• remove obsolete files
• remove two empty packages
• move private header files to src directory where relevant
• replace CLHEP/SystemOfUnits.h with the one from GaudiKernel

This merge request affects 14 packages:

• Control/AthenaExamples/AthAsgExUnittest
• Control/AthenaExamples/AthExFortranAlgorithm
• Control/AthenaExamples/AthExHelloWorld
• Control/AthenaExamples/AthExHistNtup
• Control/AthenaExamples/AthExHive
• Control/AthenaExamples/AthExJobOptions
• Control/AthenaExamples/AthExMonitored
• Control/AthenaExamples/AthExRunExamples
• Control/AthenaExamples/AthExRunHelloWorld
• Control/AthenaExamples/AthExStoreGateExample
• Control/AthenaExamples/AthExThinning
• Control/AthenaExamples/AthExUnittest
• Control/AthenaExamples/MultiInputExample
• Control/AthenaExamples/ToyConversion

Adding @ssnyder ,@rbianchi as watchers

added Core master review-pending-level-1 labels

CI Result SUCCESS (hash 403547c2)

	Athena	AthSimulation	AnalysisBase	AthGeneration
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 15497]

The changes look fine to me. Passing this to L2 for a second look.

Jason (L1)

added review-pending-level-2 label and removed review-pending-level-1 label

Looks good, approving.

added review-approved label and removed review-pending-level-2 label

merged

mentioned in commit 35905b50

added sweep:ignore label