Add devcontainer to run tests (#109)

* Add devcontainer to run tests

Includes a running build of mosquitto

* Minor docker-compose changes

Renamed setup -> app
Add CI=true (to stop running tests checking against public mqtt server inside devcontainer)

Author: adam-fowler

.devcontainer/devcontainer.json

@@ -0,0 +1,12 @@
+{
+    "name": "MQTT Swift 5.6",
+    "dockerComposeFile": "docker-compose.yml",
+    "service": "app",
+    "workspaceFolder": "/workspace",
+    "extensions": [
+      "sswg.swift-lang",
+    ],
+    "settings": {
+      "lldb.library": "/usr/lib/liblldb.so"
+    },
+}

.devcontainer/docker-compose.yml

@@ -0,0 +1,25 @@
+# run this with docker-compose -f docker/docker-compose.yml run test
+version: "3.3"
+
+services:
+  app:
+    image: swift:5.6-focal
+    volumes:
+      - ..:/workspace
+    depends_on:
+      - mosquitto
+    environment:
+      - MOSQUITTO_SERVER=mosquitto
+      - CI=true
+    command: sleep infinity
+
+  mosquitto:
+    image: eclipse-mosquitto
+    volumes:
+      - ../mosquitto/config:/mosquitto/config
+      - ../mosquitto/certs:/mosquitto/certs
+    ports:
+      - "1883:1883"
+      - "8883:8883"
+      - "8080:8080"
+      - "8081:8081"