Fixed: Xapian crash scenarios.

[MohitMaliFtechiz]

Fixes #3877

• There was a concurrency issue in the search functionality in a very specific condition, causing data corruption and race conditions when users searched for different terms simultaneously.
• Introduced a global Mutex in the SearchResultsWithTerm class to control access to search results.
• Applied the Mutex in the SearchState class to lock execution and ensure that only one coroutine can process search results at a time. Since here we are getting the data from libzim this global mutex will prevent getting data via multiple coroutines.
• Enhanced retrieval of suggestion lists from libzim.
• Implemented task cancellation if the fragment is not visible.
• Refactored getVisibleResults into a suspend method to ensure efficient job cancellation.
• Handled exceptions thrown by coroutines.
• Employed lifecycleScope for coroutine launch to prevent unnecessary calls when the fragment is hidden.
• Added unit test cases for testing the previous job is canceled properly.
• Testing the render method with different scenarios to ensure that libzim does not crash due to a broken call stack.

[codecov]

Codecov Report

Attention: Patch coverage is 76.11940% with 16 lines in your changes missing coverage. Please review.

Project coverage is 53.54%. Comparing base (9f94965) to head (193c0d1).

Files	Patch %	Lines
...rg/kiwix/kiwixmobile/core/search/SearchFragment.kt	62.50%	4 Missing and 8 partials ⚠️
...x/kiwixmobile/core/search/viewmodel/SearchState.kt	88.88%	1 Missing and 1 partial ⚠️
...wixmobile/core/search/viewmodel/SearchViewModel.kt	85.71%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3885      +/-   ##
============================================
- Coverage     53.54%   53.54%   -0.01%     
+ Complexity     1402     1396       -6     
============================================
  Files           301      302       +1     
  Lines         11569    11588      +19     
  Branches       1526     1527       +1     
============================================
+ Hits           6195     6205      +10     
- Misses         4376     4381       +5     
- Partials        998     1002       +4     

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[kelson42]

@MohitMaliFtechiz Thank you for the fix and the hard work. Does this PR has any other impact for the users (positive or negative) beside fixing the crash scenario?

@MohitMaliFtechiz Does this PR impacts #2505 as well?

[MohitMaliFtechiz]

@MohitMaliFtechiz Thank you for the fix and the hard work. Does this PR has any other impact for the users (positive or negative) beside fixing the crash scenario?

@kelson42 No it will not impact the user, it only fixes the crashing scenario.

@MohitMaliFtechiz Does this PR impacts #2505 as well?

@kelson42 This PR is for suggestions, and we are now fully using the coroutines for searching the suggestions from the zim file. But #2505 is related to FileSearching(to get the zim files from storage that is different from this PR), and for that, we are currently using the Rxjava. So this PR does not impact the #2505.