FRAME_ALLOCATOR global, make XunilFrameAllocator not hold Limine entries
so it can be used without lifetimes, implement the process struct, add
user heap by giving back heap_start from ELF and adding sbrk syscall,
align ELF loading in userspace_stub, implement lots of libc functions in
libxunil, remove x86_64 dependency from libxunil, add malloc and all
required heap functions to libxunil and more syscall numbers, add a util
file to libxunil, add build scripts for libxunil and doomgeneric
relocations, add some more functions to libxunil, use include inside of
tests instead of manually defining types and add basic libc header
files. Move libxunil to the user folder, and add helloworld and
doomgeneric as apps
implementation, running support, also basic syscalls to test if it
works. add a syscall ABI and a new libxunil ABI for calling back to the
kernel with syscalls, add user mode protection when running ELF, add TSS
Privilege Stack table to fix GPF issues, add invalid opcode handler, fix
rust panics using rectangle_filled instead of fb clear. Also add a hello
world example binary that runs in usermode at startup.
