refactor: convert DataBlock to an enum, add conversion from arrow, normalize dictionaries

[westonpace]

a lot of the logic in the conversion from arrow to data block is spread throughout the encoders (the next PR will remove this code from the encoders and change the encoders to use data block)

[westonpace]

Leaving in draft until #2784 merges

[github-actions]

ACTION NEEDED
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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 71.53946% with 220 lines in your changes missing coverage. Please review.

Project coverage is 78.53%. Comparing base (f9f151d) to head (8918ada).

Files	Patch %	Lines
rust/lance-encoding/src/data.rs	73.72%	173 Missing and 2 partials ⚠️
rust/lance-encoding/src/testing.rs	13.33%	13 Missing ⚠️
...ance-encoding/src/encodings/physical/dictionary.rs	69.44%	8 Missing and 3 partials ⚠️
rust/lance-encoding/src/encodings/physical/fsst.rs	0.00%	9 Missing ⚠️
rust/lance-encoding/src/encodings/physical.rs	20.00%	4 Missing ⚠️
...coding/src/encodings/physical/fixed_size_binary.rs	0.00%	3 Missing ⚠️
.../lance-encoding/src/encodings/logical/primitive.rs	87.50%	0 Missing and 2 partials ⚠️
...ust/lance-encoding/src/encodings/physical/basic.rs	80.00%	0 Missing and 1 partial ⚠️
...st/lance-encoding/src/encodings/physical/binary.rs	80.00%	0 Missing and 1 partial ⚠️
...encoding/src/encodings/physical/fixed_size_list.rs	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2789      +/-   ##
==========================================
+ Coverage   78.52%   78.53%   +0.01%     
==========================================
  Files         228      228              
  Lines       68641    69273     +632     
  Branches    68641    69273     +632     
==========================================
+ Hits        53902    54406     +504     
- Misses      11679    11789     +110     
- Partials     3060     3078      +18     

Flag	Coverage Δ
unittests	78.53% <71.53%> (+0.01%)	⬆️

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[broccoliSpicy]

LGTM!