Improve derive(Event) and simplify macro code (#18083)

# Objective

simplify some code and improve Event macro

Closes #14336,


# Showcase

you can now write derive Events like so
```rust
#[derive(event)]
#[event(auto_propagate, traversal = MyType)]
struct MyEvent;
```

Author: Bleachfuel

crates/bevy_ecs/macros/Cargo.toml

@@ -11,7 +11,7 @@ proc-macro = true
 [dependencies]
 bevy_macro_utils = { path = "../../bevy_macro_utils", version = "0.16.0-dev" }
 
-syn = { version = "2.0", features = ["full"] }
+syn = { version = "2.0.99", features = ["full", "extra-traits"] }
 quote = "1.0"
 proc-macro2 = "1.0"
 [lints]