Rename Add to Queue for methods with deferred semantics (#15234)

# Objective

- Fixes #15106

## Solution

- Trivial refactor to rename the method. The duplicate method `push` was
removed as well. This will simpify the API and make the semantics more
clear. `Add` implies that the action happens immediately, whereas in
reality, the command is queued to be run eventually.
- `ChildBuilder::add_command` has similarly been renamed to
`queue_command`.

## Testing

Unit tests should suffice for this simple refactor.

---

## Migration Guide

- `Commands::add` and `Commands::push` have been replaced with
`Commnads::queue`.
- `ChildBuilder::add_command` has been renamed to
`ChildBuilder::queue_command`.

benches/benches/bevy_ecs/world/commands.rs

@@ -146,9 +146,9 @@ pub fn fake_commands(criterion: &mut Criterion) {
  let mut commands = Commands::new(&mut command_queue, &world);
  for i in 0..command_count {
  if black_box(i % 2 == 0) {
- commands.add(FakeCommandA);
+ commands.queue(FakeCommandA);
  } else {
- commands.add(FakeCommandB(0));
+ commands.queue(FakeCommandB(0));
  }
  }
  command_queue.apply(&mut world);
@@ -190,7 +190,7 @@ pub fn sized_commands_impl<T: Default + Command>(criterion: &mut Criterion) {
  bencher.iter(|| {
  let mut commands = Commands::new(&mut command_queue, &world);
  for _ in 0..command_count {
- commands.add(T::default());
+ commands.queue(T::default());
  }
  command_queue.apply(&mut world);
  });

crates/bevy_ecs/src/event/writer.rs

@@ -51,7 +51,7 @@ use bevy_ecs::{
 /// //
 /// // NOTE: the event won't actually be sent until commands get applied during
 /// // apply_deferred.
-/// commands.add(|w: &mut World| {
+/// commands.queue(|w: &mut World| {
 /// w.send_event(MyEvent);
 /// });
 /// }

crates/bevy_ecs/src/observer/mod.rs

@@ -830,7 +830,7 @@ mod tests {
  ..Default::default()
  });
 
- world.commands().add(
+ world.commands().queue(
  // SAFETY: we registered `event_a` above and it matches the type of TriggerA
  unsafe { EmitDynamicTrigger::new_with_id(event_a, EventA, ()) },
  );

crates/bevy_ecs/src/observer/runner.rs

@@ -65,7 +65,7 @@ impl Component for ObserverState {
 
  fn register_component_hooks(hooks: &mut ComponentHooks) {
  hooks.on_add(|mut world, entity, _| {
- world.commands().add(move |world: &mut World| {
+ world.commands().queue(move |world: &mut World| {
  world.register_observer(entity);
  });
  });
@@ -78,7 +78,7 @@ impl Component for ObserverState {
  .as_mut()
  .descriptor,
  );
- world.commands().add(move |world: &mut World| {
+ world.commands().queue(move |world: &mut World| {
  world.unregister_observer(entity, descriptor);
  });
  });
@@ -398,7 +398,7 @@ fn hook_on_add<E: Event, B: Bundle, S: ObserverSystem<E, B>>(
  entity: Entity,
  _: ComponentId,
 ) {
- world.commands().add(move |world: &mut World| {
+ world.commands().queue(move |world: &mut World| {
  let event_type = world.init_component::<E>();
  let mut components = Vec::new();
  B::component_ids(&mut world.components, &mut world.storages, &mut |id| {

crates/bevy_ecs/src/reflect/entity_commands.rs

@@ -79,7 +79,7 @@ pub trait ReflectCommandExt {
  ///
  /// // Or even with BundleA
  /// prefab.data = boxed_reflect_bundle_a;
- /// 
+ ///
  /// // No matter which component or bundle is in the resource and without knowing the exact type, you can
  /// // use the insert_reflect entity command to insert that component/bundle into an entity.
  /// commands
@@ -174,7 +174,7 @@ pub trait ReflectCommandExt {
 
 impl ReflectCommandExt for EntityCommands<'_> {
  fn insert_reflect(&mut self, component: Box<dyn PartialReflect>) -> &mut Self {
- self.commands.add(InsertReflect {
+ self.commands.queue(InsertReflect {
  entity: self.entity,
  component,
  });
@@ -185,7 +185,7 @@ impl ReflectCommandExt for EntityCommands<'_> {
  &mut self,
  component: Box<dyn PartialReflect>,
  ) -> &mut Self {
- self.commands.add(InsertReflectWithRegistry::<T> {
+ self.commands.queue(InsertReflectWithRegistry::<T> {
  entity: self.entity,
  _t: PhantomData,
  component,
@@ -194,7 +194,7 @@ impl ReflectCommandExt for EntityCommands<'_> {
  }
 
  fn remove_reflect(&mut self, component_type_path: impl Into<Cow<'static, str>>) -> &mut Self {
- self.commands.add(RemoveReflect {
+ self.commands.queue(RemoveReflect {
  entity: self.entity,
  component_type_path: component_type_path.into(),
  });
@@ -205,7 +205,7 @@ impl ReflectCommandExt for EntityCommands<'_> {
  &mut self,
  component_type_name: impl Into<Cow<'static, str>>,
  ) -> &mut Self {
- self.commands.add(RemoveReflectWithRegistry::<T> {
+ self.commands.queue(RemoveReflectWithRegistry::<T> {
  entity: self.entity,
  _t: PhantomData,
  component_type_name: component_type_name.into(),