cdc: move changefeed options logic from encoders to cdcevent pkg

As seen in https://github.com/cockroachdb/cockroach/issues/103129, we do not support certain options for parquet. The reason is that every time we add a new format, you need to add code to the encoder to support them. These options are not encoder-specific, so we should remove the need to write code for them in each encoder. It would be much better to write the logic once in the `cdcevent` package - it should be a simple matter of tacking on extra columns to the events before they are sent to the encoders.

The list of columns which can be handled by the cdc event descriptor are
- [ ] updated
- [ ] mvcc_timestamp
- [ ] diff
- [ ] key in value
- [ ] topic in value
- [ ] resolved

Jira issue: CRDB-27937