[C++][Python] Wrap / Unwrap Functions for Other PyArrow Objects

### Describe the enhancement requested

The PyArrow C++ module provides wrapper and unwrapper functions for a variety of Arrow entities, including schemas, arrays, record batches, and tables. Examples are:
- `arrow::python::wrap_table` or `pyarrow_wrap_table`: `std::shared_ptr` to `PyObject*`
- `arrow::python::unwrap_table` or `pyarrow_unwrap_table`: `PyObject*` to `std::shared_ptr`

However, it is missing conversion functions for newer entities, like:
- Dataset
- Filesystem
- Compute Expression
- Scanner
- RecordBatchReader

It would be helpful to expose such functions for 3rd-party APIs and tools.

### Component(s)

C++, Python