[SystemDS-#3524] Multi-threading of transformdecode/[SystemDS-#3521] Improved Feature Transformations

[Isso-W]

This pull request introduces a new framework for column decoding in Apache SystemDS, with the addition of a base class ColumnDecoder and several specialized implementations (ColumnDecoderBin, ColumnDecoderComposite, ColumnDecoderRecode,ColumnDecoderPassthrough and ColumnDecoderDummycode). These changes provide a flexible and extensible structure for decoding encoded data in matrix-to-frame transformations. Below are the most important changes grouped by theme:

Core Framework for Column Decoding

• Added ColumnDecoder as an abstract base class to define the structure for decoding operations, including methods for decoding (columnDecode), handling sub-range decoding (subRangeDecoder), and metadata initialization (initMetaData). It also implements Externalizable for efficient serialization.

Current Issues

• ColumnDecoderDummycode ist not supported yet, as well as the test case ColumnDecoderMixedMethodsTest
• There are still some issues with DecoderDummyCode, it do not work together with DecoderRecode

[codecov]

Codecov Report

Attention: Patch coverage is 41.71779% with 285 lines in your changes missing coverage. Please review.

Project coverage is 72.85%. Comparing base (bc2993e) to head (61f6d39).
Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
...ime/transform/decode/ColumnDecoderPassThrough.java	17.14%	57 Missing and 1 partial ⚠️
...ntime/transform/decode/ColumnDecoderDummycode.java	33.33%	47 Missing and 3 partials ⚠️
...sds/runtime/transform/decode/ColumnDecoderBin.java	46.25%	38 Missing and 5 partials ⚠️
...ntime/transform/decode/ColumnDecoderComposite.java	47.14%	36 Missing and 1 partial ⚠️
.../runtime/transform/decode/ColumnDecoderRecode.java	61.05%	31 Missing and 6 partials ⚠️
.../sysds/runtime/transform/decode/ColumnDecoder.java	21.95%	32 Missing ⚠️
...runtime/transform/decode/ColumnDecoderFactory.java	51.72%	27 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2275      +/-   ##
============================================
- Coverage     72.95%   72.85%   -0.10%     
- Complexity    46062    46159      +97     
============================================
  Files          1479     1486       +7     
  Lines        172575   173144     +569     
  Branches      33776    33898     +122     
============================================
+ Hits         125898   126149     +251     
- Misses        37191    37481     +290     
- Partials       9486     9514      +28     

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[phaniarnab]

Thank you for the patch. I will take a look into this next week @Isso-W.
Meanwhile, please add the missing license headers to the new files.