arrow

GH-40060: [C++][Python] Basic conversion of RecordBatch to Arrow Tensor - add support for different data types (#40359)

### What changes are included in this PR?

- Added support for `RecordBatches` with fields of different type in the conversion `RecordBatch` → `Tensor`.
- Added detail of the constraints to the `RecordBatch.to_tensor()` docstrings, see https://github.com/apache/arrow/pull/40064#discussion_r1512307964.

### Are these changes tested?

Yes.

### Are there any user-facing changes?

No.
* GitHub Issue: #40060

Lead-authored-by: AlenkaF <frim.alenka@gmail.com>
Co-authored-by: Alenka Frim <AlenkaF@users.noreply.github.com>
Co-authored-by: Benjamin Kietzman <bengilgit@gmail.com>
Co-authored-by: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Signed-off-by: Joris Van den Bossche <jorisvandenbossche@gmail.com>