Support Android 12 widget target sizes

Currently, when the widget is added, it is stretched to occupy the minimum number of cells, horizontally and vertically, required to satisfy constraints for `minWidth` (set to [300dp](https://github.com/Automattic/pocket-casts-android/blob/08159691dae28cd7d982ed6b77ef027610db62df/modules/services/repositories/src/main/res/xml/widget.xml#LL2C3-L4C29)) and `minHeight` (set to [40dp](https://github.com/Automattic/pocket-casts-android/blob/08159691dae28cd7d982ed6b77ef027610db62df/modules/services/repositories/src/main/res/xml/widget.xml#LL2C3-L4C29)) constraints according to [this table](https://developer.android.com/develop/ui/views/appwidgets/layouts#anatomy_determining_size).

Goal of this task is to support targetCellSizes for devices running Android 12 or more so that the [widget can be sized more reliably](https://developer.android.com/develop/ui/views/appwidgets/layouts#specify-widget-size-constraints) across different devices with varying screen sizes.

Start with modules/services/repositories/src/main/res/xml/widget.xml and the Android documentation linked in the issue. Check how targetCellSizes should be declared for Android 12 and later while preserving the existing minWidth and minHeight constraints. Done means the widget uses target cell sizes on supported devices and remains compatible with earlier Android versions.

Written by the indexing model from the issue text.