chore: Refactor UnaryMinus serde

[andygrove]

Which issue does this PR close?

Part of #2019

Rationale for this change

What changes are included in this PR?

How are these changes tested?

[codecov-commenter]

Codecov Report

❌ Patch coverage is 75.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.64%. Comparing base (f09f8af) to head (bf4cb18).
⚠️ Report is 490 commits behind head on main.

Files with missing lines	Patch %	Lines
...main/scala/org/apache/comet/serde/arithmetic.scala	72.72%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2378      +/-   ##
============================================
+ Coverage     56.12%   57.64%   +1.52%     
- Complexity      976     1296     +320     
============================================
  Files           119      147      +28     
  Lines         11743    13513    +1770     
  Branches       2251     2389     +138     
============================================
+ Hits           6591     7790    +1199     
- Misses         4012     4453     +441     
- Partials       1140     1270     +130     

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[comphead]

lgtm thanks @andygrove