feat(kernel): add Kernel struct, MockPlatform, and simple syscalls (GetTime, GetProcessId, Yield)

crates/kernel/src/interrupt.rs

@@ -0,0 +1,15 @@
+use domain::scheduler::SchedulerDecision;
+use platform::Platform;
+use types::id::{CoreId, IrqId, ThreadId};
+
+use crate::Kernel;
+
+impl<P: Platform> Kernel<P> {
+    pub fn handle_tick(&mut self, _core: CoreId) -> SchedulerDecision {
+        SchedulerDecision::Continue
+    }
+
+    pub fn handle_interrupt(&mut self, _irq: IrqId) -> Option<ThreadId> {
+        None
+    }
+}