test: improve coverage for utility classes

[RoiSoleil]

Improved branch coverage in WordTokenizer by adding a test for the null and empty string paths.
Improved branch coverage in FeatureDetector by adding a test for the bundleContext == null path in getBundle (via getTestNgPluginVersion).

Tested classes:

• org.moreunit.util.WordTokenizer
• org.moreunit.util.FeatureDetector

Newly covered branches:

• WordTokenizer: if(string == null || string.length() == 0)
• FeatureDetector: if(bundleContext == null) in getBundle()

Edge cases added:

• Tested WordTokenizer with null and empty string arguments.
• Tested FeatureDetector explicitly passing a null BundleContext.

Rationale for mocking choices:

• BundleContext does not need to be deeply stubbed; passing null exercises the safe-fallback path within the class. Used standard assertNull() and assertFalse() for these scenarios.
• Ensured teardown via a try-finally block when overriding static state in FeatureDetector to prevent test pollution.

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PR created automatically by Jules for task 5861206656196680215 started by @RoiSoleil

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.73%. Comparing base (49adae8) to head (46b9302).

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #351      +/-   ##
============================================
+ Coverage     79.68%   79.73%   +0.04%     
- Complexity     4041     4048       +7     
============================================
  Files           511      511              
  Lines         17282    17292      +10     
  Branches       1339     1339              
============================================
+ Hits          13772    13788      +16     
+ Misses         2943     2937       -6     
  Partials        567      567              

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