Refactored JSON IO (better support for JSON and NDJSON)

[jorgecarleitao]

This PR refactors APIs to read and write to JSON and NDJSON.

Currently, writing a primitive array to JSON requires writing a list of objects (e.g. [{"a": 1}, {"a": null}]). However, JSON supports simpler representations of a primitive array, [1, null].

The same holds true for NDJSON, where we required the user to write

{"a": 1}
{"a": null}

This PR removes this, allowing users to write [1, null] and 1\nnull respectively. The previous behavior is now a particular case, via StructArray.

The APIs of json and ndjson were also separated in two distinct modules since they are sufficiently different formats. All the public API changes are shown in the changes to the examples, and the guide was updated accordingly.

[codecov]

Codecov Report

Merging #870 (1539556) into main (fca3b8d) will decrease coverage by 0.01%.
The diff coverage is 90.07%.

@@            Coverage Diff             @@
##             main     #870      +/-   ##
==========================================
- Coverage   71.52%   71.50%   -0.02%     
==========================================
  Files         335      335              
  Lines       17989    17950      -39     
==========================================
- Hits        12867    12836      -31     
+ Misses       5122     5114       -8     

Impacted Files	Coverage Δ
src/io/json/read/deserialize.rs	66.88% <75.00%> (-1.95%)	⬇️
src/io/ndjson/read/file.rs	78.57% <78.57%> (ø)
src/io/json/write/serialize.rs	85.38% <90.90%> (-0.73%)	⬇️
src/io/json/write/mod.rs	95.00% <92.85%> (-5.00%)	⬇️
src/io/json/read/infer_schema.rs	91.25% <100.00%> (+4.76%)	⬆️
src/io/ndjson/read/deserialize.rs	100.00% <100.00%> (ø)
src/io/ndjson/write/mod.rs	100.00% <100.00%> (ø)
src/error.rs	38.46% <0.00%> (-7.70%)	⬇️
src/bitmap/utils/slice_iterator.rs	87.93% <0.00%> (+1.72%)	⬆️

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