Allow to specify PARTITION BY expression for S3 table engine.
When writing to this table, multiple files will be created, with names prefixed (?) by partition key.

PARTITION BY rand() % N will be also applicable for creation of multiple files instead of one.

Motivation:

• more efficient to read;
• easier manipulation by other data processing systems.

Details of implementation:

• if s3 path contains wildcard (*), we will substitute this wildcard by the value of partition key; it can be located in file name or in part of path (in the latter case multiple directories will be created).