Duration and Instant should live in bevy_time, not bevy_utils

[alice-i-cecile]

These are obviously part of our time-like functionality, and should be stored with those functions.

[DJMcNab]

The docs page at https://docs.rs/bevy/latest/bevy/utils/struct.Duration.html is terrible.

For context, this is because of #895, which means we re-export Instant and Duration from instant.
However, on native platforms (which docs.rs uses), that Instant is just a type alias for std instant.

This seems like a significant footgun, whether or not we put lipstick on it by moving crates.

[mockersf]

A few teams actually got their foot gunned during Bevy Jam #2 by using Instant from std and discovering at the last instant that they need to use the one reexported by Bevy to work in wasm

[DJMcNab]

at the last instant

Surely you mean the last Instant?

I'm not surprised. It's really haphazard. I certainly didn't know about this.

[mockersf]

at the last instant

Surely you mean the last Instant?

Indeed. And don't call me Shirley.

[alice-i-cecile]

There's too much headache for the benefits here due to circular dependencies. See #6034 for what this change would entail.