Move extension demo to demo project (can be loaded with indev classes currently)

demo/src/main/java/net/minestom/demo/extension/TestExtension.java

@@ -0,0 +1,21 @@
+package net.minestom.demo.extension;
+
+import net.minestom.server.extensions.Extension;
+
+public class TestExtension extends Extension {
+    @Override
+    public void initialize() {
+        System.out.println("Initialize test extension");
+
+        try {
+            Class.forName("com.mysql.cj.jdbc.Driver", true, getOrigin().getClassLoader());
+        } catch (ClassNotFoundException e) {
+            e.printStackTrace();
+        }
+    }
+
+    @Override
+    public void terminate() {
+        System.out.println("Terminate test extension");
+    }
+}

demo/src/main/resources/extension.json

@@ -0,0 +1,13 @@
+{
+  "entrypoint": "net.minestom.demo.extension.TestExtension",
+  "name": "TestExtension",
+  "version": "1.0.0",
+  "externalDependencies": {
+    "repositories": [
+      { "name": "Central", "url": "https://repo1.maven.org/maven2/" }
+    ],
+    "artifacts": [
+      "mysql:mysql-connector-java:8.0.26"
+    ]
+  }
+}

src/test/java/testextension/TestExtension.java

@@ -1,24 +0,0 @@
-package testextension;
-
-import net.minestom.server.MinecraftServer;
-import net.minestom.server.extensions.Extension;
-
-public class TestExtension extends Extension {
-
-    @Override
-    public void preInitialize() {
-        System.out.println("During preinit");
-        MinecraftServer.setTerminalEnabled(false);
-        System.out.println("Mwahaha i disabled the terminal");
-    }
-
-    @Override
-    public void initialize() {
-        System.out.println("Hello from extension!");
-    }
-
-    @Override
-    public void terminate() {
-
-    }
-}

src/test/resources/extension.json

@@ -1,4 +0,0 @@
-{
-  "entrypoint": "testextension.TestExtension",
-  "name": "Test_extension"
-}