Native Parquet write only supports `file:`/`hdfs:` outputs — falls back on `s3a://`

[parthchandra]

What is the problem the feature request solves?

With spark.comet.parquet.write.enabled=true, a straightforward Parquet write still runs on Spark when the output path is an object store. CometDataWritingCommand.getSupportLevel rejects anything that isn't file: or hdfs::

if (!outputPath.startsWith("file:") && !outputPath.startsWith("hdfs:"))
  return Unsupported("Supported output filesystems: local, HDFS")

Most production Spark writes target object stores (s3a://, gs://, abfss://), so native write is effectively unavailable there today.

Steps to reproduce

-- comet enabled, spark.comet.parquet.write.enabled=true, incompatible ops allowed
INSERT OVERWRITE DIRECTORY 's3a://example-bucket/warehouse/out'
USING parquet OPTIONS (compression 'zstd')
SELECT id, name FROM src;   -- src is a native Comet scan

Explain shows Execute InsertIntoHadoopFsRelationCommand staying on Spark; extended Comet info reports the write operator as unsupported/disabled.

Describe the potential solution

No response

Additional context

No response

[comphead]

Thanks @parthchandra it makes a lot of sense