Introduce OnTopic.Attributes as a global using directive

Previously, `OnTopic.Attributes` couldn't be (easily) introduced as a global using directive (c9f6b17, #93) because of a naming conflict with `AttributeDictionary`, which existed in both `OnTopic.Attributes` and `Microsoft.AspNetCore.Mvc.ViewFeatures`. With `AttributeDictionary` renamed to `AttributeValueDictionary` (0b62fe0, #107), this can be reintroduced.

Author: JeremyCaney

OnTopic.Tests/Properties/AssemblyInfo.cs

@@ -9,6 +9,7 @@
 \-----------------------------------------------------------------------------------------------------------------------------*/
 global using System.Collections.ObjectModel;
 global using System.Diagnostics.CodeAnalysis;
+global using OnTopic.Attributes;
 global using OnTopic.Internal.Diagnostics;
 global using OnTopic.Mapping.Annotations;
 global using OnTopic.ViewModels;

OnTopic/Properties/AssemblyInfo.cs

@@ -8,6 +8,7 @@
 | USING DIRECTIVES (GLOBAL)
 \-----------------------------------------------------------------------------------------------------------------------------*/
 global using System.Diagnostics.CodeAnalysis;
+global using OnTopic.Attributes;
 global using OnTopic.Internal.Diagnostics;
 
 /*==============================================================================================================================