Replace unsafe blocks in World and DeferredWorld with safe equivalents (#17206)

# Objective

Reduce the number of unsafe blocks.

## Solution

Replaced 5 unsafe blocks with safe equivalents.

## Testing

Reusing current tests

Author: ItsDoot

crates/bevy_ecs/src/world/deferred_world.rs

@@ -75,11 +75,7 @@ impl<'w> DeferredWorld<'w> {
         &mut self,
         entity: Entity,
     ) -> Option<Mut<T>> {
-        // SAFETY:
-        // - `as_unsafe_world_cell` is the only thing that is borrowing world
-        // - `as_unsafe_world_cell` provides mutable permission to everything
-        // - `&mut self` ensures no other borrows on world data
-        unsafe { self.world.get_entity(entity)?.get_mut() }
+        self.get_entity_mut(entity).ok()?.into_mut()
     }
 
     /// Temporarily removes a [`Component`] `T` from the provided [`Entity`] and
@@ -491,13 +487,10 @@ impl<'w> DeferredWorld<'w> {
         entity: Entity,
         component_id: ComponentId,
     ) -> Option<MutUntyped<'_>> {
-        // SAFETY: &mut self ensure that there are no outstanding accesses to the resource
-        unsafe {
-            self.world
-                .get_entity(entity)?
-                .get_mut_by_id(component_id)
-                .ok()
-        }
+        self.get_entity_mut(entity)
+            .ok()?
+            .into_mut_by_id(component_id)
+            .ok()
     }
 
     /// Triggers all `on_add` hooks for [`ComponentId`] in target.

crates/bevy_ecs/src/world/mod.rs

@@ -1230,11 +1230,7 @@ impl World {
         &mut self,
         entity: Entity,
     ) -> Option<Mut<T>> {
-        // SAFETY:
-        // - `as_unsafe_world_cell` is the only thing that is borrowing world
-        // - `as_unsafe_world_cell` provides mutable permission to everything
-        // - `&mut self` ensures no other borrows on world data
-        unsafe { self.as_unsafe_world_cell().get_entity(entity)?.get_mut() }
+        self.get_entity_mut(entity).ok()?.into_mut()
     }
 
     /// Temporarily removes a [`Component`] `T` from the provided [`Entity`] and
@@ -3509,14 +3505,7 @@ impl World {
     /// This function will panic if it isn't called from the same thread that the resource was inserted from.
     #[inline]
     pub fn get_by_id(&self, entity: Entity, component_id: ComponentId) -> Option<Ptr<'_>> {
-        // SAFETY:
-        // - `&self` ensures that all accessed data is not mutably aliased
-        // - `as_unsafe_world_cell_readonly` provides shared/readonly permission to the whole world
-        unsafe {
-            self.as_unsafe_world_cell_readonly()
-                .get_entity(entity)?
-                .get_by_id(component_id)
-        }
+        self.get_entity(entity).ok()?.get_by_id(component_id).ok()
     }
 
     /// Retrieves a mutable untyped reference to the given `entity`'s [`Component`] of the given [`ComponentId`].
@@ -3530,15 +3519,10 @@ impl World {
         entity: Entity,
         component_id: ComponentId,
     ) -> Option<MutUntyped<'_>> {
-        // SAFETY:
-        // - `&mut self` ensures that all accessed data is unaliased
-        // - `as_unsafe_world_cell` provides mutable permission to the whole world
-        unsafe {
-            self.as_unsafe_world_cell()
-                .get_entity(entity)?
-                .get_mut_by_id(component_id)
-                .ok()
-        }
+        self.get_entity_mut(entity)
+            .ok()?
+            .into_mut_by_id(component_id)
+            .ok()
     }
 }