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

El issue no especifica archivos, pruebas ni puntos de entrada. Empieza revisando los patrones de componentes existentes del repositorio y las directrices enlazadas de Material Design 3 sobre skeleton-loader; después, compara las implementaciones de NativeBase y React Native Elements a las que se hace referencia. El issue no define criterios de aceptación ni qué deberían cubrir las pruebas.

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