Default for ImageAddressMode should be Repeat

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

Default for `ImageAddressMode` is, as of `0.18.1`, `ClampToEdge`. IMO `Repeat` would be a better default value. It would still work the same for uv layouts that don't overflow the 0.0-1.0 range, but uv layouts that rely on a repeating texture would work out of the box. Clamping the texture is a rare use case.

### Side Issue: It is too much work to set a texture to repeat.

Currently you either need to use `AssetServer::load_with_settings` and pass a closure, or you need to create a `.meta` file for the asset. If you choose the 1st method you can use `..default()` and specify only the fields you want to change, but 2nd method you need to specify every single field which is cumbersome. If `Repeat` was the default we wouldn't need to do this.

## What solution would you like?

Change the default from `ClampToEdge` to `Repeat`.

## What alternative(s) have you considered?

I managed to get the texture to repeat using both `load_with_settings` and `.meta` file approach. (mentioned above)

## Additional context

.