Made IO #[forbid(unsafe)]

[jorgecarleitao]

This PR adds the bytemuck dependency and replaces all instances of unsafe in the IO module by bytemuck's API, also adding #[forbid(unsafe)] to make it more explicit that our IO has no unsafe on it.

It has no performance implications, it just formalizes (in traits) our use of plain old data (Pod) as defined in bytemuck.

Thanks to the wg secure code and in particular to @Shnatsel and @tarcieri for the recommendation that led to this PR, and also to the folks at #dark-arts for confirming that the two implementations of Pod in this PR are sound.

[codecov]

Codecov Report

Merging #749 (7c11d3e) into main (4c29966) will increase coverage by 0.01%.
The diff coverage is 93.75%.

@@            Coverage Diff             @@
##             main     #749      +/-   ##
==========================================
+ Coverage   70.82%   70.84%   +0.01%     
==========================================
  Files         313      313              
  Lines       16931    16954      +23     
==========================================
+ Hits        11992    12011      +19     
- Misses       4939     4943       +4     

Impacted Files	Coverage Δ
src/io/avro/mod.rs	66.66% <ø> (ø)
src/io/csv/mod.rs	0.00% <ø> (ø)
src/io/json/mod.rs	100.00% <ø> (ø)
src/types/native.rs	21.91% <ø> (ø)
src/io/parquet/read/primitive/utils.rs	87.50% <87.50%> (+14.77%)	⬆️
src/io/ipc/read/read_basic.rs	71.31% <100.00%> (+1.02%)	⬆️
src/io/ipc/write/serialize.rs	63.70% <100.00%> (-0.26%)	⬇️
src/io/parquet/read/primitive/basic.rs	68.68% <100.00%> (ø)
src/io/parquet/read/primitive/nested.rs	57.89% <100.00%> (ø)
src/io/parquet/read/nested_utils.rs	78.43% <0.00%> (+0.98%)	⬆️
... and 1 more

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