TUN-9583: set proper url and hostname for cloudflared tail command

This commit adds support for FedRAMP environments. Cloudflared will
now dynamically configure the management hostname and API URL, switching 
to FedRAMP-specific values like `management.fed.argotunnel.com` and `https://api.fed.cloudflare.com/client/v4`
when a FedRAMP endpoint is detected.

Key to this is an enhanced `ParseToken` function, which now includes an `IsFed()`
method to determine if a management token's issuer is `fed-tunnelstore`. This allows
cloudflared to correctly identify and operate within a FedRAMP context, ensuring 
proper connectivity.

Closes TUN-9583

credentials/credentials.go

@@ -10,6 +10,8 @@ import (
 const (
 	logFieldOriginCertPath = "originCertPath"
 	FedEndpoint            = "fed"
+	FedRampBaseApiURL      = "https://api.fed.cloudflare.com/client/v4"
+	FedRampHostname        = "management.fed.argotunnel.com"
 )
 
 type User struct {