Update plugin loading, update example plugin, add ci task for testing if builds work

src/plugins/example-plugin/ExamplePlugin.ts

@@ -0,0 +1,7 @@
+import { Plugin } from "@fosscord/util";
+
+export default class TestPlugin extends Plugin {
+    onPluginLoaded(): void {
+        console.log("Hello from test plugin! IT WORKS!!!!!!!");
+    }
+}

src/plugins/example-plugin/plugin.json

@@ -0,0 +1,10 @@
+{
+    "id": "example-plugin",
+    "name": "Fosscord example plugin",
+    "authors": [
+        "The Arcane Brony"
+    ],
+    "repository": "https://github.com/fosscord/fosscord-server",
+    "license": "",
+    "index": "ExamplePlugin.js"
+}