xactmon: Deploy xactmon

`xactmon` is a new tool I developed to parse transaction notifications
from banks and automatically import them into my personal finance
tracker.  It is designed in a modular fashion, composed of three main
components:

* Receiver
* Processor
* Importer

Components communicate with one another using an AMQP exchange.
Hypothetically, there could be multipel implementations of the receiver
and importer components.  Right now, there is only a JMAP receiver,
which fetches email messages (from Fastmail), and a Firefly III
importer.  The processor is a singleton, handling notifications from the
receiver, parsing them into a normalized format, and passing them on to
the importer.  It uses a set of rules to decide how to parse the
messages, and supports using either a regular expression with named
capture groups or an Awk script to extract the relevant information.

xactmon/config.toml

@@ -0,0 +1,16 @@
+processor_rules = "/etc/xactmon/rules.toml"
+
+[jmap]
+url = "https://api.fastmail.com"
+token_file = "/run/secrets/xactmon/fastmail.token"
+
+[amqp]
+url = "amqps://xactmon@rabbitmq.pyrocufflink.blue?auth_mechanism=external"
+clientcert = "/run/secrets/rabbitmq/cert/keystore.p12"
+clientcert_password = "/run/secrets/rabbitmq/password"
+cacert = "/run/dch-ca/dch-root-ca.crt"
+
+[firefly]
+url = "https://firefly.pyrocufflink.blue"
+token_file = "/run/secrets/xactmon/firefly.token"
+error_if_duplicate_hash = false