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ARROW-4212: [C++][Python] CudaBuffer view of arbitrary device memory object

This PR implements the following new features:
1. `CudaContext::GetDeviceAddress` method
2. `pyarrow.cuda.Context.get_device_address` method
3. `pyarrow.cuda.Context.buffer_from_object` method to create a CudaBuffer view of arbitrary device memory object that implements `__cuda_array_interface__` attribute or that is `CudaBuffer` or `CudaHostBuffer` or numba `MemoryPointer` object.
4. Tests for `buffer_from_object` method

and the following improvements:
1. `pyarrow.cuda.Context.foreign_buffer` ensures that the used device memory address is valid for the given context.

Author: Pearu Peterson <pearu.peterson@gmail.com>

Closes #3439 from pearu/arrow-4212 and squashes the following commits:

ba905739 <Pearu Peterson> Add 2-D and 3-D tests. buffer_from_object requires contiguous memory input.
355fc035 <Pearu Peterson> Apply more feedback fixes.
22134da4 <Pearu Peterson> Refactor. Add tests for negative strides and reduce test cases.
dbd1cec6 <Pearu Peterson> Moved some buffer_from_objects tests under test_cuda.
562c1805 <Pearu Peterson> Change GetDeviceAddress API to use uint8_t, add C++ tests for it, update docs and apply feedback.
2726a91e <Pearu Peterson> Add buffer_from_object and get_device_address methods.
df8656f8 <Pearu Peterson> Add GetDeviceAddress method to CudaContext.