Make SystemTime available in both native and wasm (#10980)

# Objective

`Instant` and `Duration` from the `instant` crate are exposed in
`bevy_utils` to have a single abstraction for native/wasm.
It would be useful to have the same thing for
[`SystemTime`](https://doc.rust-lang.org/std/time/struct.SystemTime.html).


---

## Changelog

### Added
- `bevy_utils` now re-exposes the `instant::SystemTime` struct

Co-authored-by: Charles Bournhonesque <cbournhonesque@snapchat.com>

crates/bevy_utils/src/lib.rs

@@ -31,7 +31,7 @@ pub use cow_arc::*;
 pub use default::default;
 pub use float_ord::*;
 pub use hashbrown;
-pub use instant::{Duration, Instant};
+pub use instant::{Duration, Instant, SystemTime};
 pub use petgraph;
 pub use thiserror;
 pub use tracing;