Add initial KubeJS setup with README, configuration files, and example scripts

- Created README.txt with directory structure and usage information.
- Added common.json, client.json, and web_server.json for configuration settings.
- Introduced example server and startup scripts (main.js) for demonstration.
- Included example textures for blocks and items in the assets directory.

kubejs/config/web_server.json

@@ -0,0 +1,6 @@
+{
+  "enabled": true,
+  "port": 61423,
+  "public_address": "",
+  "auth": "XBOSSC1-zyyA1JJ7rO_8zzJwodH9_Szk7tLwj1tt-6cb"
+}