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
with_process to interact with them. User space now has it's own address
space and mapper which means we will be able to allocate memory for it.
I added a bunch of functions as stubs into libxunil which are required
for 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
