refactor: Deque

[alxkm]

Make Deque generic.
Readability improvements.
Added tests.

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

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 95.45455% with 1 line in your changes missing coverage. Please review.

Project coverage is 44.95%. Comparing base (e756a7d) to head (ec1ea8e).

Files	Patch %	Lines
...com/thealgorithms/datastructures/queues/Deque.java	95.45%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5353      +/-   ##
============================================
+ Coverage     44.59%   44.95%   +0.35%     
- Complexity     2766     2785      +19     
============================================
  Files           522      522              
  Lines         15413    15410       -3     
  Branches       2939     2939              
============================================
+ Hits           6874     6928      +54     
+ Misses         8243     8184      -59     
- Partials        296      298       +2     

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