Replaced the navArgument with savedStateHandle since they are immutable.

[MohitMaliFtechiz]

Issue seen in #4405

• Fixed: testPreviouslyLoadedArticleLoadsAgainWhenSwitchingToAnotherScreen failing in Custom apps.
• The failure was caused by immutable arguments in navBackStackEntry that could not be cleared. To work around this earlier, we replaced the reader fragment with a new one before navigating to another screen so that arguments could be reset. However, this approach had side effects: reopening the same fragment in the background triggered extra computation, since everything in the reader screen renders on the IO thread. As a result, the previously opened page was sometimes only partially rendered, and when the test navigated back, it failed to load correctly.
• To resolve this, we have completely removed the use of navArguments, as they made handling different scenarios more difficult. Instead, we now rely on the savedStateHandle and set arguments directly on the backStackEntry. These can be cleared immediately after use, ensuring they don’t affect other scenarios. This approach not only fixes the failing test but also eliminates redundant fragment rendering, reducing unnecessary work on the IO thread.
• Refactored the test cases according to savedStateHandle approach.

[codecov]

Codecov Report

❌ Patch coverage is 54.54545% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.49%. Comparing base (28964f5) to head (941a2e3).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
...r/fileselectView/effects/OpenFileWithNavigation.kt	0.00%	4 Missing ⚠️
...rg/kiwix/kiwixmobile/core/main/CoreMainActivity.kt	0.00%	4 Missing ⚠️
...bile/nav/destination/reader/KiwixReaderFragment.kt	70.00%	0 Missing and 3 partials ⚠️
...va/org/kiwix/kiwixmobile/main/KiwixMainActivity.kt	66.66%	2 Missing ⚠️
.../destination/library/local/LocalLibraryFragment.kt	75.00%	0 Missing and 1 partial ⚠️
.../kiwixmobile/core/extensions/ActivityExtensions.kt	0.00%	1 Missing ⚠️

❌ Your patch status has failed because the patch coverage (54.54%) is below the target coverage (70.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #4408      +/-   ##
============================================
+ Coverage     57.25%   57.49%   +0.23%     
- Complexity     1454     1463       +9     
============================================
  Files           328      328              
  Lines         16859    16809      -50     
  Branches       2061     2057       -4     
============================================
+ Hits           9653     9664      +11     
+ Misses         5856     5796      -60     
+ Partials       1350     1349       -1     

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