nayuos: add a promise to verify that sudo exists

on the SlapOS's host, as required to chroot in the build
environment cros_sdk

software/nayuos/instance.cfg

 [buildout]
 parts =
   parameters
+  promise-sudo-on-host
   template-full-build-script
   template-sudo-wrapper
   template-cros-sdk-wrapper
@@ -47,6 +48,7 @@ cert = ${slap_connection:cert_file}
 recipe = slapos.cookbook:mkdirectory
 log = ${buildout:directory}/var/log
 run = ${buildout:directory}/etc/run
+promise = ${buildout:directory}/etc/promise
 wrapper_dir = ${buildout:directory}/wrapper_bin
 cros_location = ${buildout:directory}/parts/chromiumos
 ebuilds_dir = ${nayuos-ebuilds:location}
@@ -58,6 +60,13 @@ wrapper_cros_sdk=${directory:wrapper_dir}/wrapper_cros_sdk
 bash=/bin/bash
 sudo=/usr/bin/sudo
 
+[promise-sudo-on-host]
+# assert sudo is installed on the slapos host, as it is required to enter the
+# chroot 'cros_sdk'
+recipe  = slapos.cookbook:wrapper
+wrapper-path = !py! '${directory:promise}/' + '${:_buildout_section_name_}'[8:]
+command-line = sudo -V
+
 [template-sudo-wrapper]
 recipe = slapos.recipe.template:jinja2
 template = {{ scripts_dir }}/wrapper_sudo.in