Add single column transformer

[krishan1390]

1. ColumnReaderTransformer wraps a columnReader and applies transform functions efficiently. It avoids Object conversion unless transformation is neccessary
2. Created ColumnTransformer interface and 2 implementations - DataTypeColumnTransformer and NullValueColumnTransformer
3. Modify DefaultValueColumnReader to always return null so that NullValueColumnTransformer takes effect. Clients need to use ColumnReaderTransformer as the wrapper for this

Objective is for above interfaces to handle single column transformations.

Multi column transformations needs to be done separately via different interface.

This depends on https://github.com/apache/pinot/pull/17293 for new methods in the ColumnReader interface

[codecov-commenter]

Codecov Report

:x: Patch coverage is 89.85507% with 14 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 63.25%. Comparing base (95d43c0) to head (94d7228). :warning: Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...l/columntransformer/DataTypeColumnTransformer.java	83.78%	2 Missing and 4 partials :warning:
.../segment/local/utils/DataTypeTransformerUtils.java	90.32%	3 Missing and 3 partials :warning:
.../columntransformer/NullValueColumnTransformer.java	85.71%	0 Missing and 1 partial :warning:
...segment/local/utils/NullValueTransformerUtils.java	96.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #17304      +/-   ##
============================================
- Coverage     63.28%   63.25%   -0.03%     
  Complexity     1474     1474              
============================================
  Files          3154     3158       +4     
  Lines        188007   188056      +49     
  Branches      28782    28793      +11     
============================================
- Hits         118977   118957      -20     
- Misses        59807    59879      +72     
+ Partials       9223     9220       -3     

Flag	Coverage Δ
custom-integration1	100.00% <ø> (ø)
integration	100.00% <ø> (ø)
integration1	100.00% <ø> (ø)
integration2	0.00% <ø> (ø)
java-11	63.23% <89.85%> (-0.04%)	:arrow_down:
java-21	63.22% <89.85%> (+<0.01%)	:arrow_up:
temurin	63.25% <89.85%> (-0.03%)	:arrow_down:
unittests	63.25% <89.85%> (-0.03%)	:arrow_down:
unittests1	55.65% <47.10%> (-0.04%)	:arrow_down:
unittests2	33.93% <89.13%> (-0.01%)	:arrow_down:

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[9aman]

Please edit the PR description. It refers to the changes that were present in the previous commits.

[rohityadav1993]

@krishan1390, can you add a plan how all the transformers will be supported in the future, current implementation is too narrow in scope and doesn't discuss long-term usability.

Also, give a brief description on the flows that will be affected/utilise the columnTransformer and if this is configurable? Segments will eventually be loaded on servers and server can detect to reprocess a segment based on the latest schema and config so it should be safe to opt out of data type transformation and be a config in segment builder.