Adds the ability to create a project using an existing in the Payload repo example through `create-payload-app`: For example: `pnpx create-payload-app --example custom-server` - creates a project from the [custom-server](https://github.com/payloadcms/payload/tree/main/examples/custom-server) example. This is much easier and faster then downloading the whole repo and copying the example to another folder. Note that we don't configure the payload config with the storage / DB adapter there because examples can be very specific.