TrigEFMissingET CMake Fixes, main branch (2024.03.20.)

This is to undo a mistake introduced in !69806 (merged), and to fix another issue that was present in the code for even longer.

• Since the shared library still needs ROOT, it has to be found explicitly by the code.
• To make sure that the component library would see the LWTNN headers reliably, ${LWTNN_INCLUDE_DIRS} also needs to be used.

The reason I noticed these mistakes is because of the "serious warnings" in the latest nightlies.

https://bigpanda.cern.ch/nview/?nightly=main_Athena_x86_64-el9-gcc13-opt

Something that the shifters should've really picked up on...

Trigger/TrigAlgorithms/TrigEFMissingET/CMakeLists.txt

@@ -4,10 +4,11 @@
 atlas_subdir( TrigEFMissingET )
 
 # External dependencies:
+find_package( ROOT COMPONENTS Matrix Physics )
 find_package( Eigen )
 find_package( lwtnn )
 
-atlas_add_library( TrigEFMissingETLib 
+atlas_add_library( TrigEFMissingETLib
    Root/*.cxx
    PUBLIC_HEADERS TrigEFMissingET
    INCLUDE_DIRS ${EIGEN_INCLUDE_DIRS} ${ROOT_INCLUDE_DIRS}
@@ -19,9 +20,10 @@ atlas_add_library( TrigEFMissingETLib
 # Component(s) in the package:
 atlas_add_component( TrigEFMissingET
    src/*.cxx src/components/*.cxx
+   INCLUDE_DIRS ${LWTNN_INCLUDE_DIRS}
    LINK_LIBRARIES
       TrigEFMissingETLib AthenaBaseComps StoreGateLib AthContainers GaudiKernel AthenaMonitoringKernelLib AthLinks
-      CaloGeoHelpers CaloEvent CaloConditions CaloIdentifier 
+      CaloGeoHelpers CaloEvent CaloConditions CaloIdentifier
       InDetTrackSelectionToolLib TrackVertexAssociationToolLib TrkCaloExtension RecoToolInterfaces JetEDM
       xAODCaloEvent xAODTrigMissingET xAODJet xAODBase xAODEventShape xAODPFlow
       PathResolver
@@ -30,4 +32,3 @@ atlas_add_component( TrigEFMissingET
 
 # Install files from the package:
 atlas_install_python_modules( python/*.py POST_BUILD_CMD ${ATLAS_FLAKE8} --extend-extensions=ATL900,ATL901 )
-