run0: implement -v/--validate to renew temporary auth

This is meant to mirror sudo's -v/--validate options, which autohrize
the user without running a command.

shell-completion/bash/run0

@@ -38,7 +38,7 @@ _run0() {
         --setenv --background
     )
     local OPTS="${opts_with_values[*]} -h --help -V --version --no-ask-password --slice-inherit --empower"
-    OPTS="$OPTS -k --reset-timestamp -K --remove-timestamp"
+    OPTS="$OPTS -k --reset-timestamp -K --remove-timestamp -v --validate"
 
     local i
     for (( i=1; i <= COMP_CWORD; i++ )); do