feat(kernel): add WaitForInterrupt, AcknowledgeInterrupt, and WaitAny syscalls

crates/domain/src/syscall.rs

@@ -11,6 +11,28 @@ pub struct WaitSet {
     interrupts: [Option<CapSlot>; 4],
 }
 
+impl WaitSet {
+    pub fn new(
+        endpoints: [Option<CapSlot>; 4],
+        interrupts: [Option<CapSlot>; 4],
+    ) -> Self {
+        Self { endpoints, interrupts }
+    }
+
+    pub fn endpoints(&self) -> &[Option<CapSlot>; 4] {
+        &self.endpoints
+    }
+
+    pub fn interrupts(&self) -> &[Option<CapSlot>; 4] {
+        &self.interrupts
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.endpoints.iter().all(|s| s.is_none())
+            && self.interrupts.iter().all(|s| s.is_none())
+    }
+}
+
 pub enum WakeReason {
     MessageReady(CapSlot),
     InterruptFired(CapSlot),