Rename Active -> Available to match new terminology

From configurator PR

Author: keveleigh

Assets/MRTK/Core/Definitions/MixedRealityToolkitConfigurationProfile.cs

@@ -169,7 +169,7 @@ public bool IsBoundarySystemEnabled
         /// <summary>
         /// Boundary system class to instantiate at runtime.
         /// </summary>
-        public SystemType BoundarySystemSystemType => (!XRSettingsUtilities.IsLegacyXRActive && xrsdkBoundarySystemType?.Type != null) ? xrsdkBoundarySystemType : boundarySystemType;
+        public SystemType BoundarySystemSystemType => (!XRSettingsUtilities.LegacyXRAvailable && xrsdkBoundarySystemType?.Type != null) ? xrsdkBoundarySystemType : boundarySystemType;
 
         [SerializeField]
         [Tooltip("Profile for wiring up boundary visualization assets.")]

Assets/MRTK/Core/Services/BaseDataProviderAccessCoreSystem.cs

@@ -216,7 +216,7 @@ private bool RegisterDataProviderInternal<T>(
 #if UNITY_2020_1_OR_NEWER
                 SupportedUnityXRPipelines.XRSDK;
 #elif UNITY_2019
-                !XRSettingsUtilities.IsLegacyXRActive ? SupportedUnityXRPipelines.XRSDK : SupportedUnityXRPipelines.LegacyXR;
+                !XRSettingsUtilities.LegacyXRAvailable ? SupportedUnityXRPipelines.XRSDK : SupportedUnityXRPipelines.LegacyXR;
 #else
                 SupportedUnityXRPipelines.LegacyXR;
 #endif

Assets/MRTK/Core/Utilities/XRSettingsUtilities.cs

@@ -16,20 +16,20 @@ namespace Microsoft.MixedReality.Toolkit.Utilities
     public static class XRSettingsUtilities
     {
 #if UNITY_2019_3_OR_NEWER
-        private static bool? isLegacyXRActive = null;
+        private static bool? legacyXRAvailable = null;
 #endif // UNITY_2019_3_OR_NEWER
 
         /// <summary>
         /// Checks if an XR SDK plug-in is installed that disables legacy VR. Returns false if so.
         /// </summary>
-        public static bool IsLegacyXRActive
+        public static bool LegacyXRAvailable
         {
             get
             {
 #if UNITY_2019_3_OR_NEWER
-                if (!isLegacyXRActive.HasValue)
+                if (!legacyXRAvailable.HasValue)
                 {
-                    isLegacyXRActive = true;
+                    legacyXRAvailable = true;
 
                     List<XRDisplaySubsystemDescriptor> descriptors = new List<XRDisplaySubsystemDescriptor>();
                     SubsystemManager.GetSubsystemDescriptors(descriptors);
@@ -38,13 +38,13 @@ public static bool IsLegacyXRActive
                     {
                         if (displayDescriptor.disablesLegacyVr)
                         {
-                            isLegacyXRActive = false;
+                            legacyXRAvailable = false;
                             break;
                         }
                     }
                 }
 
-                return isLegacyXRActive.HasValue && isLegacyXRActive.Value;
+                return legacyXRAvailable.HasValue && legacyXRAvailable.Value;
 #else
                 return true;
 #endif // UNITY_2019_3_OR_NEWER