feat(config)!: Move new_mqtt_client out of global automation table into separate module

The function `new_mqtt_client` was the last remaining entry in the
global `automation` table. The function was renamed to `new` and placed
in the new `mqtt` module. As `automation` is now empty, it has been
removed.

config.lua

@@ -23,7 +23,7 @@ local fulfillment = {
 	openid_url = "https://login.huizinga.dev/api/oidc",
 }
 
-local mqtt_client = automation.new_mqtt_client({
+local mqtt_client = require("mqtt").new({
 	host = ((host == "zeus" or host == "hephaestus") and "olympus.lan.huizinga.dev") or "mosquitto",
 	port = 8883,
 	client_name = "automation-" .. host,

src/main.rs

@@ -116,9 +116,9 @@ async fn app() -> anyhow::Result<()> {
     })?;
     lua.globals().set("print", print)?;
 
-    let automation = lua.create_table()?;
+    let mqtt = lua.create_table()?;
     let event_channel = device_manager.event_channel();
-    let new_mqtt_client = lua.create_function(move |lua, config: mlua::Value| {
+    let mqtt_new = lua.create_function(move |lua, config: mlua::Value| {
         let config: MqttConfig = lua.from_value(config)?;
 
         // Create a mqtt client
@@ -128,9 +128,8 @@ async fn app() -> anyhow::Result<()> {
 
         Ok(WrappedAsyncClient(client))
     })?;
-
-    automation.set("new_mqtt_client", new_mqtt_client)?;
-    lua.globals().set("automation", automation)?;
+    mqtt.set("new", mqtt_new)?;
+    lua.register_module("mqtt", mqtt)?;
 
     lua.register_module("device_manager", device_manager.clone())?;