Fix format, structure and compression method detection for DataLake

[ianton-ru]

Changelog category (leave one):

• Bug Fix (user-visible misbehavior in an official stable release)

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Fixed format detection for table function iceberg (fixes #732)

Documentation entry for user-facing changes

With empty Iceberg table this query works:

select * from icebergS3('http://minio:9000/warehouse/data/', 'minio', 'minio123')

and this not

select * from iceberg('http://minio:9000/warehouse/data/', 'minio', 'minio123')

Code: 715. DB::Exception: Received from localhost:9000. DB::Exception: The data format cannot be detected by the contents of the files, because there are no files with provided path in S3ObjectStorage or all files are empty. You can specify the format manually: The data format cannot be detected by the contents of the files. You can specify the format manually. (CANNOT_DETECT_FORMAT)

because StorageIcebergConfiguration returns own default-initialized fields instead of fields of specific config implementation (S3, Azure or HDFS), ClickHouse tries to resolve it and it fails - for datalake format is always 'Parquet' now, but when it not filled properly, code tries to detect it from source files and fails for empty table case.

Technical changes - fields in StorageObjectStorage::Configuration now private access via getters and setters.
Logical changes - these getters and setters are overridden in StorageIcebergConfiguration to use proper implementation.