**Use case**

For creating external data dictionary with settings (url, headers, etc.) from config.xml `<named_collections>`  for HTTP sources.
This is to allow updating per environment test, staging, prod without updating `CREATE DICTIONARY` statement, values set externally.

**Describe the solution you'd like**

Add HTTP source options as currently available for PostgreSQL, MySQL, S3 and Kafka:
https://clickhouse.com/docs/en/operations/named-collections/
keys should be `url`, `user`,`password`, `headers`.

**Describe alternatives you've considered**

use different data source for named collections.
use custom settings.

cc: @kssenii 

#pragma once
#include <Interpreters/Context.h>
#include <Poco/Util/AbstractConfiguration.h>
#include <Storages/StorageS3Settings.h>
namespace DB
{
#define EMPTY_SETTINGS(M)
DECLARE_SETTINGS_TRAITS(EmptySettingsTraits, EMPTY_SETTINGS)
struct EmptySettings : public BaseSettings<EmptySettingsTraits> {};
struct ExternalDataSourceConfiguration