Add skeleton and test files

Dockerfile

src/Makefile

src/crt/__libc_start_main.c

src/crt/start.asm

src/errno.c

src/include/errno.h

src/include/fcntl.h

src/include/internal/arch/x86_64/syscall_arch.h

src/include/internal/arch/x86_64/syscall_list.h

src/include/internal/essentials.h

src/include/internal/io.h

src/include/internal/mm/mem_list.h

src/include/internal/syscall.h

src/include/internal/types.h

src/include/stdarg.h

src/include/stddef.h

src/include/stdio.h

src/include/stdlib.h

src/include/string.h

src/include/sys/mman.h