Initial AArch64 port (#205)

* Initial aarch64 port

* Enable chainload on aarch64

No changes necessary since it's all UEFI anyway.

* Add specification for Limine protocol for aarch64

* PROTOCOL: Specify state of information in DT /chosen node

* common: Add spinup code for aarch64

* common: Port elf and term to aarch64

* common: Port vmm to aarch64

Also prepare to drop VMM_FLAG_PRESENT on x86.

* protos: Port limine boot protocol to aarch64

Also drop VMM_FLAG_PRESENT since we never unmap pages anyway.

* test: Add DTB request

* PROTOCOL: Port SMP request to aarch64

* cpu: Add cache maintenance functions for aarch64

* protos/limine, sys: Port SMP to aarch64

Also move common asm macros into a header file.

* test: Start up APs

* vmm: Unify get_next_level and implement large page splitting

* protos/limine: Map framebuffer using correct caching mode on AArch64

* CI: Fix GCC build for aarch64

* entry, menu: Replace uses of naked attribute with separate asm file

GCC does not understand the naked attribute on aarch64, and didn't
understand it for x86 in older versions.

common/menu_thunk.asm_ia32

@@ -0,0 +1,26 @@
+global menu
+extern _menu
+menu:
+    pop eax
+    call .L1
+.L1:
+    pop eax
+    add eax, .L3 - .L1
+    cmp dword [eax], 0
+    jne .L2
+    mov [eax], esp
+    jmp .L4
+
+.L2:
+    mov edi, [esp]
+    mov esp, [eax]
+    push edi
+    jmp .L4
+
+.L3:
+    dq 0
+
+.L4:
+    push 0
+    jmp _menu
+