Add %w to cache_key (dovecot's passdb args)

This way, concurrent SOGo sessions using different PT can work

root/etc/e-smith/db/configuration/defaults/dovecot/PassDBArgs

@@ -1 +1 @@
-cache_key=%n%r%l
+cache_key=%n%r%l%w

root/etc/e-smith/db/configuration/migrate/DovecotCacheKeys

@@ -0,0 +1,8 @@
+{
+  # Add the plaintext password to the cache key so concurrent sessions
+  # from SOGo, using different CAS PT can work
+  my $args = $DB->get_prop('dovecot', 'PassDBArgs');
+  if ($args && $args eq 'cache_key=%n%r%l'){
+    $DB->set_prop('dovecot', 'PassDBArgs', 'cache_key=%n%r%l%w');
+  }
+}