**Use case**

This works:

```
SELECT * FROM hits_100m_obfuscated INTO OUTFILE 'hits.csv' FORMAT CSV
```

But I want this:

```
SELECT * FROM hits_100m_obfuscated INTO OUTFILE 'hits.csv'
```

**Describe the solution you'd like**

Every format can register file extension(s) in format factory.
If format is not specified explicitly, we can detect it automatically by file extension.
It should work for compressed files `hits.csv.gz` as well.

The following extensions should be supported at least:
csv, tsv, parquet, orc, native, json, ndjson, xml, md, avro

**Addition details**

Let's also support omitting the format argument for `file`, `url`, `s3`, `hdfs` table functions. 
#pragma once
#include <Common/Allocator.h>
#include <Columns/IColumn.h>
#include <Formats/FormatSettings.h>
#include <Interpreters/Context_fwd.h>
#include <IO/BufferWithOwnMemory.h>
#include <base/types.h>
#include <Core/NamesAndTypes.h>
#include <boost/noncopyable.hpp>
#include <functional>
#include <memory>
#include <unordered_map>
namespace DB
{
class Block;