[Concurrency] Fix ptr auth for task priority escalation handler

We missed to sign the handler. Along the way the signature of it
changed, so adjust for that.

How to get the number:

```
func PROPER(bar: (TaskPriority, TaskPriority) -> Void) {
    let p = TaskPriority.default
    bar(p, p)
}
```

```
-> % swiftc -target arm64e-apple-macos13 example.swift -S -o - | swift demangle | grep -a3 autda
	stur	x8, [x29, #-64]
	mov	x17, x8
	movk	x17, #11839, lsl #48 <<<<<<<<<
	autda	x16, x17
	ldr	x8, [x16, #64]
	lsr	x8, x8, #0
	add	x8, x8, #15
```

Resolves rdar://150378890

Author: ktoso

include/swift/ABI/MetadataValues.h

@@ -1745,7 +1745,7 @@ namespace SpecialPointerAuthDiscriminators {
   const uint16_t AsyncContextParent = 0xbda2; // = 48546
   const uint16_t AsyncContextResume = 0xd707; // = 55047
   const uint16_t AsyncContextYield = 0xe207; // = 57863
-  const uint16_t CancellationNotificationFunction = 0x1933; // = 6451
+  const uint16_t CancellationNotificationFunction = 0x2E3F; // = 11839 (TaskPriority, TaskPriority) -> Void
   const uint16_t EscalationNotificationFunction = 0x7861; // = 30817
   const uint16_t AsyncThinNullaryFunction = 0x0f08; // = 3848
   const uint16_t AsyncFutureFunction = 0x720f; // = 29199

stdlib/public/Concurrency/Task.cpp

@@ -1812,8 +1812,9 @@ swift_task_addPriorityEscalationHandlerImpl(
     void *context) {
   void *allocation =
       swift_task_alloc(sizeof(EscalationNotificationStatusRecord));
+  auto unsigned_handler = swift_auth_code(handler, 11839);
   auto *record = ::new (allocation)
-      EscalationNotificationStatusRecord(handler, context);
+      EscalationNotificationStatusRecord(unsigned_handler, context);
 
   addStatusRecordToSelf(record, [&](ActiveTaskStatus oldStatus, ActiveTaskStatus& newStatus) {
     return true;