…sier for

other components to adopt.

Currently, the only way for custom components that participate in
rendering to opt into the higher-performance extraction method in bevyengine#9903
is to implement the `RenderInstances` data structure and the extraction
logic manually. This is inconvenient compared to the `ExtractComponent`
API.

This commit creates a new `ExtractToRenderInstance` trait that mirrors
the existing `ExtractComponent` method but uses the higher-performance
approach that bevyengine#9903 uses. This makes high-performance rendering
components essentially as easy to write as the existing ones based on
component extraction.