Add tests, remove `main`, improve docs in `FibonacciSearch`

[Hardvan]

• [x] I have read CONTRIBUTING.md.
• [x] This pull request is all my own work -- I have not plagiarized it.
• [x] All filenames are in PascalCase.
• [x] All functions and variable names follow Java naming conventions.
• [x] All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• [x] All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 60.79%. Comparing base (ca5fbbf) to head (ffb8a74).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5665      +/-   ##
============================================
+ Coverage     60.56%   60.79%   +0.22%     
- Complexity     3896     3911      +15     
============================================
  Files           563      563              
  Lines         16023    16026       +3     
  Branches       3072     3075       +3     
============================================
+ Hits           9705     9743      +38     
+ Misses         5910     5876      -34     
+ Partials        408      407       -1     

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