build: add a "user" arch to allow the kernel to run as a program on the host machine

arch/user/extra.mk

@@ -0,0 +1,13 @@
+run: $(BUILD_DIR)/$(KERNEL_EXEC)
+	@printf "    \033[1;93mEXEC\033[0m   $<\n"
+
+	@$(BUILD_DIR)/$(KERNEL_EXEC)
+
+debug: $(BUILD_DIR)/$(KERNEL_EXEC)
+	@if command -v gdb &> /dev/null; then \
+		gdb -tui $(BUILD_DIR)/$(KERNEL_EXEC) \
+	elif commad -v lldb &> /dev/null; then \
+		lldb -- $(BUILD_DIR)/$(KERNEL_EXEC) \
+	else \
+		printf "No debuggers available." \
+	endif