Added url() function and URL table engine in ClickHouse

Why it matters

These features provide the ability to query data directly from URLs, enabling users to work with external data sources over HTTP or HTTPS as if they were tables in ClickHouse. This simplifies data ingestion and integration workflows by allowing direct access to remote resources without manual downloading or preprocessing.

How to use it

Use the url() table function to specify a URL as a data source in your queries, or create a table using the URL table engine to treat the contents of a URL as a table. For example, you can query data from a web resource using:

SELECT * FROM url('http://example.com/data.csv', 'CSV');

or create a table with the URL engine:

CREATE TABLE example_table ENGINE = URL('http://example.com/data.csv', 'CSV');