Add support for skeleton loaders

**Is your feature request related to a problem? Please describe.**
This is not related to a problem, just a desirable feature.

**Describe the solution you'd like**
It would be amazing if we could have an opinionated implementation of skeleton loaders [as defined in MD3](https://m3.material.io/styles/motion/transitions/transition-patterns#f7ff608a-087d-4a4e-9e83-f1af69184487).

**Describe alternatives you've considered**
There is a plethora of open source libraries providing this feature, although with debatable APIs and performance.

**Additional context**
As of today, the bar for truly great UX is really high and skeleton loaders are one of the building blocks that contribute to achieve that. Other component libraries provide those out of the box (e.g. [NativeBase](https://docs.nativebase.io/skeleton), [React Native Elements](https://reactnativeelements.com/docs/next/components/skeleton)), IMHO it wouldn't be unreasonable to think that `react-native-paper` users should be able to find those in the component section.

https://github.com/callstack/react-native-paper/assets/8156463/bc415ede-7ee5-4efb-9c4f-746d5013df50