L1CaloFEX[ToolInterfaces]: cmake and package cleanups

L1CaloFEX:

• remove atlas_depends_on_subdirs
• enable flake8 and fix code
• fixes to component declaration

L1CaloFEXToolInterfaces:

• cmake fix for interface library

Trigger/TrigT1/L1CaloFEXToolInterfaces/CMakeLists.txt

-################################################################################
-# Package: L1CaloFEXToolInterfaces
-################################################################################
+# Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 
 # Declare the package name:
 atlas_subdir( L1CaloFEXToolInterfaces )
 
-# Declare the package's dependencies:
-atlas_depends_on_subdirs( PUBLIC
-                          Control/AthenaBaseComps 
-			  GaudiKernal
-			  )
-
 atlas_add_library( L1CaloFEXToolInterfaces
+                   L1CaloFEXToolInterfaces/*.h
+                   INTERFACE
                    PUBLIC_HEADERS L1CaloFEXToolInterfaces
-                   LINK_LIBRARIES AthenaBaseComps CaloEvent xAODTrigL1Calo CaloIdentifier )#GaudiKernal )
+                   LINK_LIBRARIES AthenaBaseComps CaloEvent CaloIdentifier GaudiKernel L1CaloFEXSimLib xAODTrigL1Calo )