Table with no current snapshot throws on time travel filter with different schema

### Apache Iceberg version

1.11.0 (latest release)

### Query engine

None

### Please describe the bug 🐞

https://github.com/apache/iceberg/pull/13301 fixed https://github.com/apache/iceberg/issues/11162, but not for the case where the table currently has no snapshot.

For example, consider a WAP-style workflow where a table has snapshots potentially with different schemas, but does not have a snapshot on its main branch yet. If those snapshots with non-main schemas are read via time travel, planning a filter on a column that existed in the snapshot fails with e.g. (see https://github.com/apache/iceberg/pull/17735 for the failing test here)

```
Cannot find field 'data' in struct: struct<1: id: required long, 3: part: required string>
```

This is the same problem as in the above PR / issue, except the fix PR included a `currentSnapshot() == null` special case that causes the issue to remain when the table has no snapshots.

### Willingness to contribute

- [x] I can contribute a fix for this bug independently
- [ ] I would be willing to contribute a fix for this bug with guidance from the Iceberg community
- [ ] I cannot contribute a fix for this bug at this time

Start by reading issue 11162 and pull request 13301, then inspect the failing test described in pull request 17735. Reproduce the time-travel filter failure for a table with no current snapshot and snapshots using different schemas. Done means the filter can resolve the column from the time-travel snapshot without the reported missing-field error.

Written by the indexing model from the issue text.