**Use case**
ClickHouse as a web server becomes a viable scenario.
(At least in backoffice).

**Describe the solution you'd like**
Add this field.

**Additional context**
It's in question how to name it. The original HTTP specs has the famous typo in it and name it `referer`. While JavaScript has this typo fixed and name it `referrer`.

class ReadBuffer;
/** Information about client for query.
  * Some fields are passed explicitly from client and some are calculated automatically.
  *
  * Contains info about initial query source, for tracing distributed queries
  *  (where one query initiates many other queries).
  */
class ClientInfo
{
public:
    enum class Interface : uint8_t
    {
        TCP = 1,
        HTTP = 2,
        GRPC = 3,
        MYSQL = 4,
        POSTGRESQL = 5,
    };
    enum class HTTPMethod : uint8_t
    {
        UNKNOWN = 0,
        GET = 1,
        POST = 2,
    };
    enum class QueryKind : uint8_t