Add the ability to copy memory to non resident process.

Use/Test this by loading the user space elf from the kernel process
before it starts rather than as a part of the first thread.

This simplifies thread start a fair bit.

zion/loader/elf_loader.h

@@ -3,4 +3,4 @@
 #include <stdint.h>
 
 // Loads the elf program and returns its entry point.
-uint64_t LoadElfProgram(uint64_t base, uint64_t length);
+uint64_t LoadElfProgram(uint64_t cr3, uint64_t base, uint64_t length);