Migrated the IntroScreen to use DataStore instead of SharedPreferences.

[MohitMaliFtechiz]

Fixes #4517

Parent PR #4516

Continuing from #4516

• Migrated the IntroScreen functionality to use DataStore.
• Refactored all related UI test cases to use DataStore instead of SharedPreferences.
• Added a migration test case to verify the transfer of data from SharedPreferences to DataStore.

[codecov]

Codecov Report

❌ Patch coverage is 65.20000% with 87 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.01%. Comparing base (0b14cf6) to head (77a0f69).

Files with missing lines	Patch %	Lines
...kiwixmobile/core/utils/datastore/KiwixDataStore.kt	65.51%	12 Missing and 8 partials ⚠️
...estination/library/online/OnlineLibraryFragment.kt	20.83%	15 Missing and 4 partials ⚠️
...kiwixmobile/core/main/reader/CoreReaderFragment.kt	29.41%	3 Missing and 9 partials ⚠️
...kiwix/kiwixmobile/core/utils/ExternalLinkOpener.kt	10.00%	9 Missing ⚠️
...rg/kiwix/kiwixmobile/core/main/CoreMainActivity.kt	0.00%	6 Missing ⚠️
.../kiwixmobile/core/settings/CoreSettingsFragment.kt	20.00%	2 Missing and 2 partials ⚠️
...wix/kiwixmobile/core/settings/SettingsPresenter.kt	42.85%	4 Missing ⚠️
.../kiwixmobile/core/extensions/FragmentExtensions.kt	50.00%	1 Missing and 2 partials ⚠️
...obile/core/settings/viewmodel/SettingsViewModel.kt	93.33%	3 Missing ⚠️
...loader/downloadManager/DownloadManagerRequester.kt	60.00%	0 Missing and 2 partials ⚠️
... and 5 more

❌ Your patch check has failed because the patch coverage (65.20%) 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    #4518      +/-   ##
============================================
+ Coverage     58.96%   59.01%   +0.05%     
- Complexity     1520     1541      +21     
============================================
  Files           324      327       +3     
  Lines         17500    17640     +140     
  Branches       2179     2185       +6     
============================================
+ Hits          10318    10411      +93     
- Misses         5757     5796      +39     
- Partials       1425     1433       +8     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.