Add an example demonstrating integration with fluent for localization

[alice-i-cecile]

This is an important wrinkle, and it would be great to showcase how this fits together.

[brandon-reinhart]

The way I do this is implement Display for Id that writes Id's in hex 0xDEADBEEF. I then can insert these into labels with a prefix:
"item0xDEADBEEF" or pass them as tokens to fluent strings "crafting?item_type=item0xDEADBEEF".

Then I have a system that resolves all Text components that also have a UiLocalize component. Resolution involves first replacing the hex with the matching manifest entry's name "crafting?item_type=wood" and then passing that to bevy_fluent's content fn.

There are probably steps that could be removed, maybe the interim hex encoding, but I found that's useful for eyeballing problems.

Another neat thing you can do is mark any strings that fallback with a custom TextColor, so if you're playing in French, strings that fail to localize in French and fallback to English will show up red or whatever.