This patch replaces the usage of the deprecated FingerprintManager API with
BiometricPrompt. This uses the Android X library, so we get the native biometric
prompt on recent versions of Android and a Google-made one on older versions. By
not working with custom prompts for biometric authentication like we do now, we
can be sure that any issues like #70, #81, #237 are not actually our fault.
Here's what it looks like:

As a nice aside, this also adds support for the new facial recognition as an
authentication method on Pixel 4 phones.
This is still a draft, but early feedback is welcome.
This also fixes an issue with the use of the Iconics library where it was
initialized twice. I also removed the dependency to [AndroidX Preference
eXtended](https://github.com/takisoft/preferencex-android), as there don't seem
to be any issues with using the vanilla AndroidX preference library anymore.
This patch introduces the new ``UUIDMap`` type, reducing code duplication and
making UUID lookups faster. We currently already use UUIDs as the identifier for
the ``DatabaseEntry`` and ``Slot`` types, but the way lookups by UUID work are
kind of ugly, as we simply iterate over the list until we find a match. As we're
probably going to have more types like this soon (groups and icons, for
example), I figured it'd be good to abstract this away into a separate type and
make it a map instead of a list.
The only thing that has gotten slower is the ``swap`` method. The internal
``LinkedHashMap`` retains insertion order with a linked list, but does not know
about the position of the values, so we basically have to copy the entire map to
simply swap two values. I don't think it's too big of a deal, because swap
operations still take less than a millisecond even with large vaults, but
suggestions for improving this are welcome.
I had to update gradle and JUnit to be able to use the new ``assertThrows``
assertion method, so this patch includes that as well.
This patch adds a dependency to glide to handle the loading and caching of
icons. In my testing it eliminated the lag previously experienced in the main
activity when quickly scrolling through a large list of entries. It does add an
extra 1MB to the APK size, but I think that's acceptable for the amount of
complexity it handles for us.