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.
### What?
Migrates the `form-builder` example to payload `3.0`.
`Updates`:
- Now has a next app directly along side payload.
- Removes `form-builder/next-app` & `form-builder/next-pages` example
front-ends and only uses new recommended approach (i.e admin panel &
front-end on the same port - `3000`)