[Feature Request]: snapshot usability: snapshot merge

### Is there an existing issue for the same feature request?

- [x] I have checked the existing issues.

### Is your feature request related to a problem?

```Markdown
Snapshot merge t t2 {snapshot} [skip|accept|fail when conflict]

Merge T2 into t. T and t2 may or may not be same table. But requires same schema.

Diff3 t t2 and apply the diff to T. When has primary key, there could be conflicts, in which case we either,
Fail, error. This is default.
Skip, keep t values
Accept,keep t2 values.
```

### Describe the feature you'd like

If t and t2 has clone lineage, it should be fast.

### Describe implementation you've considered

_No response_

### Documentation, Adoption, Use Case, Migration Strategy

```Markdown

```

### Additional information

_No response_