feat: Added kotlin devcontainer

kotlin/devcontainer.json

@@ -0,0 +1,26 @@
+{
+  "name": "Kotlin",
+  "image": "git.luke-else.co.uk/luke-else/kotlin-dev:latest",
+  "remoteUser": "dev",
+
+  "customizations": {
+    "vscode": {
+      "settings": {
+        "terminal.integrated.defaultProfile.linux": "zsh",
+        "editor.formatOnSave": true,
+        "java.jdt.ls.java.home": "/usr/lib/jvm/java-21-openjdk"
+      },
+      "extensions": [
+        "ms-azuretools.vscode-docker",
+        "ms-vscode-remote.remote-containers",
+        "fwcd.kotlin",
+        "vscjava.vscode-gradle",
+        "redhat.java",
+        "esbenp.prettier-vscode"
+      ]
+    }
+  },
+
+  "postCreateCommand": "gradle build",
+  "runArgs": ["--init"]
+}