Time travel support

Several databases and data lakes support time travel which allows historical versions of a table to be queried. Regrettably, syntax and capabilities do not seem to be terribly consistent across the various implementations.

## Querying Historical Times

This option lets a database be queried as it existed at a certain point in time. (*Question:* Is this "last version prior to the given time"? or is it an error if no snapshot exists with that exact time?)

### [Databricks](https://docs.databricks.com/gcp/en/delta/history#delta-time-travel-syntax)

```
SELECT * FROM people10m TIMESTAMP AS OF '2018-10-18T22:15:12.013Z';
```

### [Snowflake](https://docs.snowflake.com/en/sql-reference/constructs/at-before)

```
SELECT * FROM my_table AT(TIMESTAMP => 'Wed, 26 Jun 2024 09:20:00 -0700'::TIMESTAMP_LTZ);
```

### [Cockroach](https://www.cockroachlabs.com/blog/time-travel-queries-select-witty_subtitle-the_future/)

```
SELECT * FROM t AS OF SYSTEM TIME '2016-06-15 12:45:00'
```

### [DuckLake](https://ducklake.select/docs/stable/duckdb/usage/time_travel.html)

```
SELECT * FROM tbl AT (TIMESTAMP => now() - INTERVAL '1 week');
```

## Querying Specific versions

This options lets a specific "version" of a database to be queried. What exactly this means seems to depend on the database implementation in question.

### Databricks

```
SELECT * FROM people10m VERSION AS OF 123;
```

### Snowflake

Note: unclear if this is the same thing (specific versions) or different

```
SELECT * FROM my_table BEFORE(STATEMENT => '8e5d0ca9-005e-44e6-b858-a8f5b37c5726');
```

### Cockroach

Unsupported

### DuckLake

```
SELECT * FROM tbl AT (VERSION => 3);
```

In der Issue sind keine Repository-Dateien, Tests oder Einstiegspunkte angegeben. Beginnen Sie mit dem Vergleich der Syntax von Databricks, Snowflake, Cockroach und DuckLake und klären Sie, ob Abfragen zu historischen Zeitpunkten und Versionen dieselbe Semantik haben oder dialektspezifisch bleiben sollten. Der Abschluss sollte einen vereinbarten Umfang für die unterstützte Syntax und das unterstützte Verhalten enthalten.

Vom Indexierungsmodell aus dem Issue-Text verfasst.