Convert EMotionFX runtime uint32 -> size_t

This allows the EMotionFX runtime to compile with `/we4267` enabled, which
emits a warning when converting from `size_t` to a smaller type. All tests
for the runtime have been updated accordingly, and they pass.

In instances where a range-for loop could be used, or a std algorithm, that
was used instead of using `size_t numItems = vec.size()` and a for loop.

Casts to `uint32` were removed where possible. Some places remain, like in
the file formats.

Signed-off-by: Chris Burel <burelc@amazon.com>

Gems/EMotionFX/Code/Tests/AnimGraphParameterConditionCommandTests.cpp

@@ -47,7 +47,7 @@ namespace EMotionFX
             newParameter->SetName(parameterName);
             CommandSystem::ConstructCreateParameterCommand(commandString, m_animGraph.get(),
                 newParameter.get(),
-                MCORE_INVALIDINDEX32);
+                InvalidIndex);
 
             EXPECT_TRUE(commandManager.ExecuteCommand(commandString, result)) << result.c_str();
         }