Add support to extension types in FFI

[jorgecarleitao]

With this PR, exporting and import the extension datatype roundtrips.

Pyarrow equivalent being worked at apache/arrow#11071

[codecov]

Codecov Report

Merging #363 (6a304cc) into main (98b4f17) will increase coverage by 0.00%.
The diff coverage is 88.88%.

@@           Coverage Diff           @@
##             main     #363   +/-   ##
=======================================
  Coverage   81.13%   81.14%           
=======================================
  Files         326      326           
  Lines       21150    21173   +23     
=======================================
+ Hits        17160    17180   +20     
- Misses       3990     3993    +3     

Impacted Files	Coverage Δ
src/datatypes/mod.rs	69.49% <ø> (ø)
src/io/ipc/convert.rs	94.91% <ø> (-0.08%)	⬇️
src/io/json_integration/schema.rs	44.58% <ø> (ø)
src/ffi/schema.rs	66.07% <84.61%> (+1.45%)	⬆️
src/datatypes/field.rs	29.36% <100.00%> (+4.15%)	⬆️
tests/it/ffi.rs	100.00% <100.00%> (ø)

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