feat: add testing of string/binary to 2.1 full-zip encoding and fix bugs

[westonpace]

The bugs mostly originated from having def information but no rep information since the variable full zip path was originally built to support lists.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 65.76577% with 38 lines in your changes missing coverage. Please review.

Project coverage is 78.80%. Comparing base (58c5e27) to head (83859d1).

Files with missing lines	Patch %	Lines
rust/lance-encoding/src/repdef.rs	49.05%	27 Missing ⚠️
.../lance-encoding/src/encodings/logical/primitive.rs	81.13%	10 Missing ⚠️
rust/lance-encoding/src/testing.rs	80.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3418      +/-   ##
==========================================
- Coverage   78.81%   78.80%   -0.02%     
==========================================
  Files         250      250              
  Lines       91306    91365      +59     
  Branches    91306    91365      +59     
==========================================
+ Hits        71963    71998      +35     
- Misses      16390    16409      +19     
- Partials     2953     2958       +5     

Flag	Coverage Δ
unittests	78.80% <65.76%> (-0.02%)	⬇️

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