Implement passphrase generation for db (closes #173) (#224) (#233)

* Implement passphrase generation for db (closes #173) (#224)

* Add failing tests (#173)

* Fix AppDatabase instance not reset when method called (#173)

* Implement passphrase generation and storage/retrieval of passphrase by encrypted shared preferences (#173)

* Setup Retention while maintaining the DB Password

Signed-off-by: d067928 <jakob.moeller@sap.com>

* Setup Retention while maintaining the DB Password

Signed-off-by: d067928 <jakob.moeller@sap.com>

* Lint

Signed-off-by: d067928 <jakob.moeller@sap.com>

Co-authored-by: Andreas Schattney <a.schattney@gmail.com>
Co-authored-by: Philipp Woessner <64482866+pwoessner@users.noreply.github.com>