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GH-35531: [Python] C Data Interface PyCapsule Protocol (#37797)

### Rationale for this change

### What changes are included in this PR?

* A new specification for Arrow PyCapsules and related dunder methods
* Implementing the dunder methods for `DataType`, `Field`, `Schema`, `Array`, `RecordBatch`, `Table`, and `RecordBatchReader`.

### Are these changes tested?

Yes, I've added various roundtrip tests for each of the types.

### Are there any user-facing changes?

This introduces some new APIs and documents them.

* Closes: #34031
* Closes: #35531

Authored-by: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Signed-off-by: Antoine Pitrou <antoine@python.org>