feat(kernel): SystemControl cap for halt, board device table + boot caps to init, RegionAddress syscall, idle loop services irqs

crates/kernel/src/syscall/mod.rs

@@ -92,6 +92,10 @@ impl<P: Platform> Kernel<P> {
                 self.map_region_cap(pid, region, va, perms)
                     .map(|()| SyscallResult::Ok),
             ),
+            Syscall::RegionAddress { region } => complete(
+                self.region_address_cap(pid, region)
+                    .map(|pa| SyscallResult::Value(pa.raw())),
+            ),
             Syscall::Delegate {
                 slot,
                 to_endpoint,
@@ -136,7 +140,7 @@ impl<P: Platform> Kernel<P> {
             Syscall::AcknowledgeInterrupt { irq } => {
                 complete(self.ack_interrupt(pid, irq).map(|()| SyscallResult::Ok))
             }
-            Syscall::Halt => self.handle_halt(pid),
+            Syscall::Halt { control } => self.handle_halt(pid, control),
             Syscall::CreateEndpoint => self.handle_create_endpoint(pid),
             Syscall::DebugPutchar { byte } => self.handle_debug_putchar(byte),
             Syscall::MapPage {