Add configurable HTTP client to Loginradius struct

[sanjayjohn]

Summary

• Added HTTPRClient *httprutils.Client field to the Loginradius struct, enabling consumers to inject a custom HTTP client
• Replaced all 157 occurrences of httprutils.TimeoutClient.Send(...) with lr.Client.HTTPRClient.Send(...) across 22 API files
• Backward compatible: NewLoginradius() defaults HTTPRClient to httprutils.TimeoutClient

Usage

lrclient, _ := lr.NewLoginradius(&cfg)
// Optionally inject a custom HTTP client:
lrclient.HTTPRClient = &httprutils.Client{HTTPClient: customHTTPClient}