`bevy_image::TextureAtlasBuilder`: Edge protection example

## What problem does this solve or what need does it fill?

Either add an example demonstrating texture atlas edge protection using padding and extrusion, or add something to an exisiting example that does the same.

Start with the bevy_image::TextureAtlasBuilder API and the existing examples that use it. Identify where an example can demonstrate edge protection through padding and extrusion, then verify that the example clearly shows both settings and produces the intended protected texture atlas.

Written by the indexing model from the issue text.