[Feature] Migrate existing table to Paimon table

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/incubator-paimon/issues) and found nothing similar.

### Motivation

Generate Paimon managed metadata files for parquet/avro/orc data files to convert existing table to Paimon managed table.

### Solution

_No response_

### Anything else?

_No response_

### Are you willing to submit a PR?

- [X] I'm willing to submit a PR!

Start by reviewing the Paimon repository's existing table and metadata-generation paths, with attention to parquet, avro, and orc data files. The issue does not name files, tests, an entry point, or a concrete solution; define the conversion behavior and validation criteria before implementation.

Written by the indexing model from the issue text.