Rename serverUrl option to serverOrigin

[hdodov]

As the Payload docs say:

Option	Description
serverURL	A string used to define the absolute URL of your app including the protocol, for example https://example.com. No paths allowed, only protocol, domain and (optionally) port

Since no paths are allowed and only the protocol, domain, and port are permitted, then this is not actually a URL, but rather an origin. Here's how web.dev describes "origin":

"Origin" is a combination of a scheme (also known as the protocol, for example HTTP or HTTPS), hostname, and port (if specified). For example, given a URL of https://www.example.com:443/foo , the "origin" is https://www.example.com:443.

In other words, what the Payload docs describe is exactly an origin.

It'd be great if Payload introduces this at some point and turns:

• serverUrl to serverOrigin
• process.env.SERVER_URL to process.env.SERVER_ORIGIN