Allocators for audio system file cache (#1485)

* Reinstates an allocator for FileCacheManager

Replaces the allocator that was removed during redcode that is used for
loading banks.  Default schema for now to get things working again.

* Update path functions to AZ::IO::Path

Removes old PathUtil functions in favor of AZ::IO::Path apis.

* Update the audio allocator classes

Cleans up the audio allocator classes a bit.

* Addresses PR feedback

Updates some code to handle nullptr a bit better, and improve log
messages.

* Updates to audio CVars and address feedback

Per feedback, converted more of the audio cvars to AZ_CVAR, but not all
of them could be converted at this time.  Moved audio allocator
initialization to system component ctor/dtor to give RAII.  Updated
location of a PAL file.

* Updates the copyright of the file added in this PR

Merged copyright changes, so need to update new files.

Gems/AudioSystem/Code/Source/AudioSystemGemSystemComponent.h

@@ -32,7 +32,6 @@ namespace AudioSystemGem
     {
     public:
         AZ_COMPONENT(AudioSystemGemSystemComponent, "{55095EE9-38E6-485F-8314-DF35CDFECC6B}", AZ::Component);
-
         static void Reflect(AZ::ReflectContext* context);
 
         static void GetProvidedServices(AZ::ComponentDescriptor::DependencyArrayType& provided);
@@ -40,6 +39,9 @@ namespace AudioSystemGem
         static void GetRequiredServices(AZ::ComponentDescriptor::DependencyArrayType& required);
         static void GetDependentServices(AZ::ComponentDescriptor::DependencyArrayType& dependent);
 
+        AudioSystemGemSystemComponent();
+        ~AudioSystemGemSystemComponent() override;
+
     protected:
         ////////////////////////////////////////////////////////////////////////
         // AZ::Component interface implementation