Add last_changed_tick and added_tick to ComponentTicks (#8803)

# Objective

EntityRef::get_change_ticks mentions that ComponentTicks is useful to
create change detection for your own runtime.

However, ComponentTicks doesn't even expose enough data to create
something that implements DetectChanges. Specifically, we need to be
able to extract the last change tick.

## Solution

We add a method to get the last change tick. We also add a method to get
the added tick.

## Changelog

- Add `last_changed_tick` and `added_tick` to `ComponentTicks`

Author: nicopap

crates/bevy_ecs/src/component.rs

@@ -744,18 +744,30 @@ pub struct ComponentTicks {
 }
 
 impl ComponentTicks {
-    #[inline]
     /// Returns `true` if the component was added after the system last ran.
+    #[inline]
     pub fn is_added(&self, last_run: Tick, this_run: Tick) -> bool {
         self.added.is_newer_than(last_run, this_run)
     }
 
-    #[inline]
     /// Returns `true` if the component was added or mutably dereferenced after the system last ran.
+    #[inline]
     pub fn is_changed(&self, last_run: Tick, this_run: Tick) -> bool {
         self.changed.is_newer_than(last_run, this_run)
     }
 
+    /// Returns the tick recording the time this component was most recently changed.
+    #[inline]
+    pub fn last_changed_tick(&self) -> Tick {
+        self.changed
+    }
+
+    /// Returns the tick recording the time this component was added.
+    #[inline]
+    pub fn added_tick(&self) -> Tick {
+        self.added
+    }
+
     pub(crate) fn new(change_tick: Tick) -> Self {
         Self {
             added: change_tick,