fix(panettone): Automatically reconnect to ldap

Wrap all ldap access in a macro that automatically reconnects and
retries operations that fail due to a connection error, to handle the
case where the ldap server restarts while we still have an open
connection.

Fixes: #44
Change-Id: I4859cf509106e480f97fed17e7f08e0eea909352
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1871
Tested-by: BuildkiteCI
Reviewed-by: eta <eta@theta.eu.org>

web/panettone/src/panettone.lisp

@@ -571,6 +571,8 @@
 
 (comment
  (setq hunchentoot:*catch-errors-p* nil)
+ ;; to setup an ssh tunnel to ldap+cheddar for development:
+ ;; ssh -NL 3899:localhost:389 -L 4238:localhost:4238 whitby.tvl.fyi
  (start-panettone :port 6161
                   :ldap-port 3899
                   :session-secret "session-secret")