[#1573] added LiveChat OAuth2 provider

Co-authored-by: Marios Antonoudiou <m.antonoudiou@celonis.com>

tools/auth/auth.go

@@ -110,6 +110,8 @@ func NewProviderByName(name string) (Provider, error) {
 		return NewStravaProvider(), nil
 	case NameGitee:
 		return NewGiteeProvider(), nil
+	case NameLivechat:
+		return NewLivechatProvider(), nil
 	default:
 		return nil, errors.New("Missing provider " + name)
 	}