fix: restore previous session data on app opening

[falconandy]

Summary

1. Current session restore logic didn't work correctly due to Kotlin initialization order (property initializes, init blocks, child/parent inheritance). The logic is extracted to a separate init block.
2. Added a test for the session restore logic.
3. Session-specific code is moved from coroutines to let it be executed synchronously and avoid possible data-race issues.
4. Some unnecessary code is removed (including previousSessionId property)
5. Fixed bug in InMemoryStorage - contains was used instead of containsKey

Checklist

• [x] Does your PR title have the correct title format?
• Does your PR have a breaking change?: No

[github-actions[bot]]

:tada: This PR is included in version 1.4.6 :tada:

The release is available on:

• GitHub release
• v1.4.6

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