Changed global::Utilities namespace to deeper namespace:

[alexandre-mckinnon]

• Under src/FastSerialization: namespace Utilities becomes namespace FastSerialization.Utilities
• Under src/PerfView: namespace Utilities becomes namespace PerfView.Utilities
• Under src/TraceEvent: namespace Utilities becomes namespace Microsoft.Diagnostics.Tracing.Utilities
• Under src/Utilities: namespace Utilities becomes namespace Microsoft.Diagnostics.Utilities

Fixes issue #1049

[msftclas]

All CLA requirements met.