feat: Better examples, dedicated example space, refactoring methods

[Bluefinger]

Closes #53

This PR contains a revamped examples section for bevy_rand to showcase some more advanced applications of its features. Simple use-cases are already well covered by the documentation. This should provide a better way for users to see how they could potentially leverage bevy_rand further beyond just the simple. To prevent the examples polluting the workspace with far more dev dependencies, it's been made its own workspace separate from the root. In future, this will allow doing further examples pulling in other crates in the ecosystem for further showcasing.

With the PR comes with some breaking changes after dogfooding the APIs with the examples, which should make bevy_rand nicer to use going forward by making a few less assumptions. All changes have been documented in the migration guide.