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GH-43894: [R] format_aggregation() should print options too (#43896)

### Rationale for this change

If you printed the inner query after summarize, it would show what function was being called but not the function options.

### What changes are included in this PR?

One-line code change plus a test

### Are these changes tested?

Yes. Interestingly, it did not seem that `format_aggregations()` was tested before.

### Are there any user-facing changes?

Technically yes, but few users would likely see this.
* GitHub Issue: #43894

Authored-by: Neal Richardson <neal.p.richardson@gmail.com>
Signed-off-by: Nic Crane <thisisnic@gmail.com>