Copy the `2d_shapes` example to the new `bevy_examples` crate

The `2d_shapes ` is chosen because it’s the most basic example that contains bevy feathers, to ensure the `bevy_examples` crate is set up correctly.

Copy this example to this new crate. We copy for now to ensure that existing example systems aren’t broken — Don’t remove its old place in the code yet.

Find the existing `2d_shapes` example and the new `bevy_examples` crate, then compare their structure and configuration. Copy the example into the new crate without removing its original location; done means both copies remain available and the new crate setup works.

Written by the indexing model from the issue text.