MINOR: acme: renewal notification over the dpapi sink

MINOR: acme: renewal notification over the dpapi sink

Output a sink message when the certificate was renewed by the ACME
client.

The message is emitted on the "dpapi" sink, and ends by \n\0.
Since the message contains this binary character, the right -0 parameter
must be used when consulting the sink over the CLI:

Example:

	$ echo "show events dpapi -nw -0" | socat -t9999 /tmp/haproxy.sock -
	<0>2025-05-19T15:56:23.059755+02:00 acme newcert foobar.pem.rsa\n\0

When used with the master CLI, @@1 should be used instead of @1 in order
to keep the connection to the worker.

Example:

	$ echo "@@1 show events dpapi -nw -0" | socat -t9999 /tmp/master.sock -
	<0>2025-05-19T15:56:23.059755+02:00 acme newcert foobar.pem.rsa\n\0