Update unhandled exception handler API to match approved shape.

src/coreclr/nativeaot/Test.CoreLib/src/System/Runtime/ExceptionServices/ExceptionHandling.cs

@@ -5,10 +5,8 @@
 
 namespace System.Runtime.ExceptionServices
 {
-    public delegate bool UnhandledExceptionHandler(System.Exception exception);
-
     public static class ExceptionHandling
     {
-        internal static UnhandledExceptionHandler? s_handler;
+        internal static Func<Exception, bool>? s_handler;
     }
 }

src/libraries/System.Private.CoreLib/src/System/Runtime/ExceptionServices/ExceptionHandling.cs

@@ -5,18 +5,16 @@
 
 namespace System.Runtime.ExceptionServices
 {
-    public delegate bool UnhandledExceptionHandler(System.Exception exception);
-
     public static class ExceptionHandling
     {
-        internal static UnhandledExceptionHandler? s_handler;
+        internal static Func<Exception, bool>? s_handler;
 
         /// <summary>
         /// Sets a handler for unhandled exceptions.
         /// </summary>
         /// <exception cref="ArgumentNullException">If handler is null</exception>
         /// <exception cref="InvalidOperationException">If a handler is already set</exception>
-        public static void SetUnhandledExceptionHandler(UnhandledExceptionHandler handler)
+        public static void SetUnhandledExceptionHandler(Func<Exception, bool> handler)
         {
             ArgumentNullException.ThrowIfNull(handler);
 

src/libraries/System.Runtime/ref/System.Runtime.cs

@@ -302,7 +302,7 @@ public event System.EventHandler? ProcessExit { add { } remove { } }
         public event System.ResolveEventHandler? ReflectionOnlyAssemblyResolve { add { } remove { } }
         public event System.ResolveEventHandler? ResourceResolve { add { } remove { } }
         public event System.ResolveEventHandler? TypeResolve { add { } remove { } }
-        public event System.UnhandledExceptionEventHandler? UnhandledException { add { } remove { } }
+        public event Func<Exception, bool>? UnhandledException { add { } remove { } }
         [System.ObsoleteAttribute("AppDomain.AppendPrivatePath has been deprecated and is not supported.")]
         public void AppendPrivatePath(string? path) { }
         public string ApplyPolicy(string assemblyName) { throw null; }
@@ -7551,7 +7551,6 @@ public UnhandledExceptionEventArgs(object exception, bool isTerminating) { }
         public object ExceptionObject { get { throw null; } }
         public bool IsTerminating { get { throw null; } }
     }
-    public delegate void UnhandledExceptionEventHandler(object sender, System.UnhandledExceptionEventArgs e);
     public partial struct ValueTuple : System.Collections.IStructuralComparable, System.Collections.IStructuralEquatable, System.IComparable, System.IComparable<System.ValueTuple>, System.IEquatable<System.ValueTuple>, System.Runtime.CompilerServices.ITuple
     {
         object? System.Runtime.CompilerServices.ITuple.this[int index] { get { throw null; } }