kernel/vm: Move most kernel debugger routines to a new vm_debug.cpp.

Reduces the size of vm.cpp by over 800 lines.
No behavioral change intended.

headers/private/kernel/vm/vm.h

@@ -144,6 +144,7 @@ status_t vm_put_physical_page_debug(addr_t vaddr, void* handle);
 void vm_get_info(system_info *info);
 uint32 vm_num_page_faults(void);
 off_t vm_available_memory(void);
+off_t vm_available_memory_debug(void);
 off_t vm_available_not_needed_memory(void);
 off_t vm_available_not_needed_memory_debug(void);
 size_t vm_kernel_address_space_left(void);

headers/private/kernel/vm/vm_priv.h

@@ -31,6 +31,8 @@ status_t vm_page_fault(addr_t address, addr_t faultAddress, bool isWrite,
 	bool isExecute, bool isUser, addr_t *newip);
 void vm_unreserve_memory(size_t bytes);
 status_t vm_try_reserve_memory(size_t bytes, int priority, bigtime_t timeout);
+
+void vm_debug_init();
 status_t vm_daemon_init(void);
 
 const char *page_state_to_string(int state);