Fixes app session logic bug

[superwall-team]

Changes in this pull request

Modifies logic in AppSessionLogic to properly determine new session. Modifies tests with proper values.

Checklist

• [x] All tests pass. Demo project builds and runs.
• [x] I added tests, an experiment, or detailed why my change isn't tested.
• [x] I added an entry to the CHANGELOG.md for any breaking changes, enhancements, or bug fixes.
• [x] I have updated the SDK documentation as well as the online docs.
• [x] I have reviewed the contributing guide