Add Unit tests for EditorFocusMode and PrefabFocus. Minor change to PrefabFocusHandler to avoid instantiating a new AZ::EntityId() for checks.

Signed-off-by: Danilo Aimini <82231674+AMZN-daimini@users.noreply.github.com>

Code/Framework/AzToolsFramework/Tests/aztoolsframeworktests_files.cmake

@@ -34,6 +34,7 @@ set(FILES
     EntityTestbed.h
     FileFunc.cpp
     FingerprintingTests.cpp
+    FocusMode/EditorFocusModeTests.cpp
     GenericComponentWrapperTest.cpp
     InstanceDataHierarchy.cpp
     IntegerPrimtitiveTestConfig.h
@@ -50,6 +51,7 @@ set(FILES
     Prefab/Benchmark/PrefabLoadBenchmarks.cpp
     Prefab/Benchmark/PrefabUpdateInstancesBenchmarks.cpp
     Prefab/Benchmark/SpawnableCreateBenchmarks.cpp
+    Prefab/PrefabFocus/PrefabFocusTests.cpp
     Prefab/MockPrefabFileIOActionValidator.cpp
     Prefab/MockPrefabFileIOActionValidator.h
     Prefab/PrefabDuplicateTests.cpp