Added the file picker in play store variant for move or copy the zim files in application's public directory

[MohitMaliFtechiz]

Fixes #3941

• Added the file picker in the playStore variant to copy/move the zim files in the application's public directory so that the user can read those sideloaded zim files in the PS variant.
• Fixed the OnBackInvokedCallback, which was not enabled for the application.
• Fixed some memory leaks of SearchFragment, KiwixPrefFragment, and LanguageFragment.
• Added the unit and instrumentation test cases for testing the whole functionality with edge cases.

https://github.com/user-attachments/assets/664466bf-6b03-49d3-9ca9-81659e36b927

The above video shows the whole functionality.

• At first launch if the user clicks on the cancel button it will again show the permission dialog.
• When the user clicks on the copy or move button in the permission dialog then it starts copying or moving the zim file based on the user's action, and it will not show the permission dialog again.
• In the third attempt I clicked on the move button so the zim file is moved from the location to the public directory as you can see in the last effort the zim file is not showing on the selected location.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 48.20359% with 173 lines in your changes missing coverage. Please review.

Project coverage is 57.73%. Comparing base (992ebc9) to head (e5d7b2a). Report is 12 commits behind head on main.

Files with missing lines	Patch %	Lines
...ile/nav/destination/library/CopyMoveFileHandler.kt	51.47%	85 Missing and 30 partials :warning:
...le/nav/destination/library/LocalLibraryFragment.kt	25.00%	39 Missing :warning:
...rg/kiwix/kiwixmobile/core/search/SearchFragment.kt	27.27%	1 Missing and 7 partials :warning:
...kiwix/kiwixmobile/core/utils/dialog/KiwixDialog.kt	65.00%	7 Missing :warning:
...org/kiwix/kiwixmobile/language/LanguageFragment.kt	50.00%	0 Missing and 4 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #3979 +/- ## ============================================ - Coverage 57.81% 57.73% -0.08% - Complexity 1572 1575 +3 ============================================ Files 310 311 +1 Lines 12549 12865 +316 Branches 1590 1641 +51 ============================================ + Hits 7255 7428 +173 - Misses 4246 4347 +101 - Partials 1048 1090 +42 ```

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