Move GCMemoryInfo to shared partition

Signed-off-by: dotnet-bot <dotnet-bot@microsoft.com>

Author: jkotas

src/System.Private.CoreLib/shared/System.Private.CoreLib.Shared.projitems

@@ -233,6 +233,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\FlagsAttribute.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\FormatException.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\FormattableString.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\GCMemoryInfo.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Gen2GcCallback.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\BidiCategory.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\Calendar.cs" />

src/System.Private.CoreLib/shared/System/GCMemoryInfo.cs

@@ -0,0 +1,56 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System
+{
+    public readonly struct GCMemoryInfo
+    {
+        /// <summary>
+        /// High memory load threshold when the last GC occured
+        /// </summary>
+        public long HighMemoryLoadThresholdBytes { get; }
+
+        /// <summary>
+        /// Memory load when the last GC ocurred
+        /// </summary>
+        public long MemoryLoadBytes { get; }
+
+        /// <summary>
+        /// Total available memory for the GC to use when the last GC ocurred. By default this is the physical memory on the machine, but it may be customized by specifying a HardLimit.
+        /// </summary>
+        public long TotalAvailableMemoryBytes { get; }
+
+        /// <summary>
+        /// The total heap size when the last GC ocurred
+        /// </summary>
+        public long HeapSizeBytes { get; }
+
+        /// <summary>
+        /// The total fragmentation when the last GC ocurred
+        ///
+        /// Let's take the example below:
+        ///  | OBJ_A |     OBJ_B     | OBJ_C |   OBJ_D   | OBJ_E |
+        ///
+        /// Let's say OBJ_B, OBJ_C and and OBJ_E are garbage and get collected, but the heap does not get compacted, the resulting heap will look like the following:
+        ///  | OBJ_A |           F           |   OBJ_D   |
+        ///
+        /// The memory between OBJ_A and OBJ_D marked `F` is considered part of the FragmentedBytes, and will be used to allocate new objects. The memory after OBJ_D will not be
+        /// considered part of the FragmentedBytes, and will also be used to allocate new objects
+        /// </summary>
+        public long FragmentedBytes { get; }
+
+        internal GCMemoryInfo(long highMemoryLoadThresholdBytes,
+                              long memoryLoadBytes,
+                              long totalAvailableMemoryBytes,
+                              long heapSizeBytes,
+                              long fragmentedBytes)
+        {
+            HighMemoryLoadThresholdBytes = highMemoryLoadThresholdBytes;
+            MemoryLoadBytes = memoryLoadBytes;
+            TotalAvailableMemoryBytes = totalAvailableMemoryBytes;
+            HeapSizeBytes = heapSizeBytes;
+            FragmentedBytes = fragmentedBytes;
+        }
+    }
+}