test: improve coverage for util package (JavaType, MemberJumpHistory, SearchScopeSingleton)

[RoiSoleil]

Increases coverage for pure utility/helper classes in the org.moreunit.util package:

• Added JavaTypeTest to cover the JavaType POJO parsing methods completely.
• Augmented MemberJumpHistoryTest to cover the previously untested singleton instantiation method.
• Added SearchScopeSingeltonTest to cover the singleton instantiation and reset cache methods for SearchScopeSingelton.

All testing relies on lightweight Mocks rather than PDE UI tests, fulfilling the issue guidelines safely without altering any production behavior.

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PR created automatically by Jules for task 2995972303736252489 started by @RoiSoleil

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.99%. Comparing base (27e8fd3) to head (247a1c2).

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #323      +/-   ##
============================================
+ Coverage     74.92%   74.99%   +0.06%     
- Complexity     3438     3448      +10     
============================================
  Files           444      446       +2     
  Lines         15394    15433      +39     
  Branches       1294     1294              
============================================
+ Hits          11534    11574      +40     
+ Misses         3331     3330       -1     
  Partials        529      529              

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