Plugins Available on Asset Library and OpenUPM

Hey! If you're using Pixelpart with Godot or Unity, it's now easier than ever to get started:

The official plugins are now listed on the Godot Asset Library and OpenUPM.

• The Godot plugin is available on the Godot Aset Library
• The Unity plugin is available on OpenUPM

Additionally, I've renamed the base Unity plugin from net.pixelpart to net.pixelpart.core to better comply with Unity's package guidelines. Make sure to remove net.pixelpart when updating.

Thank you for using Pixelpart!