Add support for the predictive back gesture

[naveensingh]

Checklist

• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• I have read the FAQs inside the app (Menu -> About -> FAQs), in the README and my problem isn't listed.
• I have taken the time to fill in all the required details. I understand that the request may get dismissed otherwise.
• This issue contains only one feature request.

Which apps should have this feature?

All Fossify Apps

Feature description

Support predictive back animation on all screens in all Fossify apps.

Why do you want this feature?

Consistent UI/UX across apps.

Additional information

This is a nice-to-have feature that will require some work to switch to the new callback-based approach. Currently, all screens intercept the back gesture by default, which disables the animation (because I found it easier to do it this way when increasing the target API level).

More info at https://developer.android.com/guide/navigation/custom-back/predictive-back-gesture