mod_http_oauth2: Namespace the various codes to minimize confusion Both for the programmer and in OAuth flows. While unlikely, it should not be possible to cause weirdness e.g. by typing a client id and authorization code into the device code entry.

This module lets you block connections to any remote servers not on a
whitelist.

``` {.lua}
modules_enabled = {
    -- other modules --
    "s2s_whitelist",

}
s2s_whitelist = {
    "example.org",
}
```