[FEAT] Add option to accept lower fingerprint security level

Hello,

Thanks Philipp for your work on Keepass2Android!

Since the update to Android 13 for Fairphone 3(+), the fingerprint sensor at the back of the device can no longer be used to log into certain apps with higher security requirements, such as some banking apps.
This issue is caused by updated Android security requirements and the lack of support from [Fairphone's] fingerprint sensor manufacturer.

Source

As a consequence, Keepass2Android (together with some other apps) is no longer accessible with the fingerprint reader.

I would like to request a new option under the 'Security' category, which would make the app accept the lower security level.

I'm not even sure this would be technically possible to change on runtime, but I'm asking because Fairphone speaks of 'apps with higher security requirements', so I assume it's something that an app declares.

Start by investigating how Android exposes fingerprint security levels and how Keepass2Android currently handles fingerprint login and its Security settings. Confirm whether accepting a lower level is technically possible at runtime, then define the setting's behavior and security implications before implementation.