Summary:
If a requests fails due to lack of allow-listing or other incompatibilities, we will now fall back to VPN mode while logging an error that will hopefully end up at the plugin owner.
For this, there's a new `vpnMode` option on every request that can also be used to enforce a particular type.
There's a lot of verbose logging that's turned off by default but very handy when debugging. Also potentially useful for plugin authors that are looking into request issues.
Reviewed By: lblasa
Differential Revision: D49023365
fbshipit-source-id: 755393063e379587feda9ae13973877780a1d987
777632b841