Expose NativeLibrary APIs (#34567)

Expose the System.Runtime.Interop.NativeLibrary APIs implemented in CoreCLR.

API review: #32015
CoreCLR Change: dotnet/coreclr#21821

Tests for the API are here:
https://github.com/dotnet/coreclr/blob/master/tests/src/Interop/NativeLibrary/NativeLibraryTests.cs

Author: swaroop-sridhar

src/System.Runtime.InteropServices/ref/System.Runtime.InteropServices.cs

@@ -730,6 +730,16 @@ protected MarshalDirectiveException(System.Runtime.Serialization.SerializationIn
         public MarshalDirectiveException(string message) { }
         public MarshalDirectiveException(string message, System.Exception inner) { }
     }
+    public static partial class NativeLibrary
+    {
+        public static void Free(System.IntPtr handle) { }
+        public static System.IntPtr GetExport(System.IntPtr handle, string name) { throw null; }
+        public static System.IntPtr Load(string libraryPath) { throw null; }
+        public static System.IntPtr Load(string libraryName, System.Reflection.Assembly assembly, DllImportSearchPath? searchPath) { throw null; }
+        public static bool TryGetExport(IntPtr handle, string name, out IntPtr address) { throw null; }
+        public static bool TryLoad(string libraryPath, out System.IntPtr handle) { throw null; }
+        public static bool TryLoad(string libraryName, System.Reflection.Assembly assembly, DllImportSearchPath? searchPath, out System.IntPtr handle) { throw null; }
+    }
     [System.AttributeUsageAttribute((System.AttributeTargets)(2048), Inherited = false)]
     public sealed partial class OptionalAttribute : System.Attribute
     {

src/System.Runtime.InteropServices/src/ApiCompatBaseline.netcoreappaot.txt

@@ -16,4 +16,5 @@ MembersMustExist : Member 'System.Runtime.InteropServices.Marshal.GetExceptionPo
 MembersMustExist : Member 'System.Runtime.InteropServices.Marshal.GetEndComSlot(System.Type)' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'System.Runtime.InteropServices.Marshal.IsTypeVisibleFromCom(System.Type)' does not exist in the implementation but it does exist in the contract.
 TypeCannotChangeClassification : Type 'System.Runtime.InteropServices.HandleRef' is marked as readonly in the contract so it must also be marked readonly in the implementation.
-Total Issues: 15
+TypesMustExist : Type 'System.Runtime.InteropServices.NativeLibrary' does not exist in the implementation but it does exist in the contract.
+Total Issues: 16

src/System.Runtime.InteropServices/src/ApiCompatBaseline.uapaot.txt

@@ -16,4 +16,5 @@ MembersMustExist : Member 'System.Runtime.InteropServices.Marshal.GetExceptionPo
 MembersMustExist : Member 'System.Runtime.InteropServices.Marshal.GetEndComSlot(System.Type)' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'System.Runtime.InteropServices.Marshal.IsTypeVisibleFromCom(System.Type)' does not exist in the implementation but it does exist in the contract.
 TypeCannotChangeClassification : Type 'System.Runtime.InteropServices.HandleRef' is marked as readonly in the contract so it must also be marked readonly in the implementation.
-Total Issues: 17
+TypesMustExist : Type 'System.Runtime.InteropServices.NativeLibrary' does not exist in the implementation but it does exist in the contract.
+Total Issues: 18