Add ArrayBuilder::finish_cloned()

[tustvold]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

The various array builders, provide a finish method which consumes the buffers, resetting the builder in the process.

When implementing a write path it is common to want to be able to "snapshot" a builder into an immutable Array for query, whilst retaining the builder state to allow for subsequent updates.

Describe the solution you'd like

Add a ArrayBuilder::finish_cloned() method that instead of consuming the buffers, clones the values.

i.e.

let mut builder = Int32Builder::new();
builder.append_value(23);
builder.append_value(45);
assert_eq!(builder.finish_cloned(), Int32Array::from(vec![23, 45]));
builder.append_value(56);
assert_eq!(builder.finish_cloned(), Int32Array::from(vec![23, 45, 56]));

Describe alternatives you've considered

Additional context

[askoa]

I'll pick this one.

Edit: I would like to submit a draft PR with small change and get comments before proceeding with all required changes.

[askoa]

@tustvold Can you take a look at the draft commit and let me know if I can extend the changes to all array builders?

[alamb]

label_issue.py automatically added labels {'arrow'} from #3158