major refactorings

Signed-off-by: kaguya3311 <kaguya3311@national.shitposting.agency>

src/arch/x86_64/serial/serial.h

@@ -0,0 +1,9 @@
+#pragma once
+
+#define COM1 0x3F8
+
+void serial_init(void);
+void serial_putchar(char ch);
+void serial_puts(char *str);
+char serial_get_byte(void);
+char serial_getchar(void);