feat: implement core initialization and local APIC setup

kernel/include/util/msr.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include "util/number.h"
+
+inline uint64_t msr_read(uint32_t msr) {
+    uint32_t low = 0;
+    uint32_t high = 0;
+    __asm__ volatile("rdmsr" : "=a"(low), "=d"(high) : "c"(msr));
+    return (static_cast<uint64_t>(high) << 32) | low;
+}
+
+inline void msr_write(uint32_t msr, uint64_t value) {
+    uint32_t low = static_cast<uint32_t>(value);
+    uint32_t high = static_cast<uint32_t>(value >> 32);
+    __asm__ volatile("wrmsr" : : "c"(msr), "a"(low), "d"(high));
+}