ATOM-15358 : Culling concurrency checker fails in AtomSampleViewer (merge from 1.0->main)

Inserting, updating, and removing entries from a VisibilityScene was made thread safe in a previous change, and now both the MeshFeatureProcessor and DiffuseProbeGridFeatureProcessor update entries at the same time from multiple threads. This leads to an assert in the Culling concurrency_checker, even though this is now valid behavior.

However, we still don't want to be adding, removing, or updating cullables between BeginCulling and EndCulling, which could cause a mismatch between the result of OctreeScene::GetEntryCount and the actual number of cullables in the scene.

-Added soft_lock_shared/soft_unlock_shared to the concurrency checker to allow multiple threads to acquire a lock when that is the desired behavior, while still asserting that nothing tries to acquire a shared lock when the concurrency checker is already locked.
-Update Culling.cpp to use the new soft_lock_shared when adding, updating, or removing cullables
-Added unit tests for the concurrency_checker
-Updated ArrayView unit test to use AZ_TEST_START_TRACE_SUPPRESSION instead of manually checking the assertion count, so that test now passes in release builds which do not assert.

Code/Framework/AtomCore/Tests/ArrayView.cpp

@@ -293,15 +293,12 @@ namespace UnitTest
     {
         array_view<int> view({ 1,2,3,4 });
 
-        UnitTest::TestRunner::Instance().StartAssertTests();
+        AZ_TEST_START_TRACE_SUPPRESSION;
 
-        EXPECT_EQ(0, UnitTest::TestRunner::Instance().m_numAssertsFailed);
         view[4];
-        EXPECT_EQ(1, UnitTest::TestRunner::Instance().m_numAssertsFailed);
         view[5];
-        EXPECT_EQ(2, UnitTest::TestRunner::Instance().m_numAssertsFailed);
 
-        UnitTest::TestRunner::Instance().StopAssertTests();
+        AZ_TEST_STOP_TRACE_SUPPRESSION(2);
     }
 
 }