Fixed FFI and added support for nested types

[jorgecarleitao]

This PR:

• Fixes the FFI implementation to output the correct number of buffers (it was always 3, now it depends on DataType)
• Adds support for nested types ([Large]List and Struct)
• Adds FFI integration tests against pyarrow==4
• Exposes function with currently allocated bytes (to check them as part of the integration tests)

MIRI reports no leaks or UB in unit-tests. Allocations from C++ and Rust report no leaks in integration tests.

[codecov]

Codecov Report

Merging #67 (3c6832e) into main (932a85d) will increase coverage by 0.07%.
The diff coverage is 68.81%.

@@            Coverage Diff             @@
##             main      #67      +/-   ##
==========================================
+ Coverage   64.76%   64.83%   +0.07%     
==========================================
  Files         187      191       +4     
  Lines       18241    18395     +154     
==========================================
+ Hits        11813    11926     +113     
- Misses       6428     6469      +41     

Impacted Files	Coverage Δ
arrow-pyarrow-integration-testing/src/lib.rs	0.00% <0.00%> (ø)
src/alloc/mod.rs	95.71% <0.00%> (-2.82%)	⬇️
src/array/boolean/ffi.rs	0.00% <0.00%> (ø)
src/array/dictionary/mod.rs	39.02% <0.00%> (+1.81%)	⬆️
src/array/fixed_size_binary/mod.rs	46.00% <0.00%> (ø)
src/array/fixed_size_list/mod.rs	60.86% <0.00%> (ø)
src/array/list/mod.rs	70.12% <ø> (+5.84%)	⬆️
src/array/null.rs	26.08% <0.00%> (ø)
src/array/struct_.rs	42.62% <0.00%> (-13.90%)	⬇️
src/buffer/bytes.rs	39.28% <ø> (ø)
... and 13 more

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