Add EventWriter::new() to allow for creation outside of module

Field should not be pub to avoid violating guarantees, so we get a constructor instead

Author: alice-i-cecile

crates/bevy_ecs/src/event.rs

@@ -168,6 +168,10 @@ impl<'a, T: Component> SystemParam for EventWriter<'a, T> {
 }
 
 impl<'a, T: Component> EventWriter<'a, T> {
+    pub fn new(events: &'a mut Events<T>) -> Self {
+        EventWriter::<'a, T> { events }
+    }
+
     pub fn send(&mut self, event: T) {
         self.events.send(event);
     }

crates/bevy_ecs/src/query/event.rs

@@ -7,7 +7,6 @@ use crate::{
     component::{Component, ComponentId, StorageType},
     prelude::World,
     storage::{Table, Tables},
-    world::Mut,
 };
 use std::any::TypeId;
 
@@ -77,13 +76,13 @@ impl<'a, T: Component> Fetch<'a> for EventWriterFetch<T> {
             .write_fetch
             .archetype_fetch(archetype_index)
             .into_inner();
-        EventWriter { events }
+        EventWriter::new(events)
     }
 
     /// Returns the EventWriter<T> of the next entity when the storage type of the query is dense
     unsafe fn table_fetch(&mut self, table_row: usize) -> Self::Item {
         let events = self.write_fetch.archetype_fetch(table_row).into_inner();
-        EventWriter { events }
+        EventWriter::new(events)
     }
 }
 struct EventWriterState<T> {