Kernel: Add time since boot to Shell

kernel/arch/i386/boot.S

@@ -12,11 +12,7 @@
 	.long MB_MAGIC
 	.long MB_FLAGS
 	.long MB_CHECKSUM
-	.skip 4
+	.skip 20
-	.skip 4
-	.skip 4
-	.skip 4
-	.skip 4
 
 	.long 0
 	.long 800

kernel/kernel/Shell.cpp

@@ -234,6 +234,10 @@ namespace Kernel
 				break;
 			}
 
+			case Keyboard::Key::Escape:
+				kprintln("time since boot {} ms", PIT::ms_since_boot());
+				break;
+
 			case Keyboard::Key::Tab:
 				break;