Feat: add sequential in gc policy (#3701)

* Feat: add sequential in gc policy

Signed-off-by: FogDong <dongtianxin.tx@alibaba-inc.com>

* tidy the code

Signed-off-by: FogDong <dongtianxin.tx@alibaba-inc.com>

* add suite test

Signed-off-by: FogDong <dongtianxin.tx@alibaba-inc.com>

* add example docs and update the field

Signed-off-by: FogDong <dongtianxin.tx@alibaba-inc.com>

* fix lint

Signed-off-by: FogDong <dongtianxin.tx@alibaba-inc.com>

* change the name to dependency

Signed-off-by: FogDong <dongtianxin.tx@alibaba-inc.com>

docs/examples/app-with-policy/gc-policy/reverse-dependency.md

@@ -0,0 +1,50 @@
+# How to garbage collect resources in the order of dependency
+
+If you want to garbage collect resources in the order of dependency, you can add `order: dependency` in the `garbage-collect` policy.
+
+> Notice that this order policy is only valid for the resources that are created in the components.
+
+In the following example, component `test1` depends on `test2`, and `test2` need the output from `test3`.
+
+So the order of deployment is: `test3 -> test2 -> test1`.
+
+When we add `order: dependency` in `garbage-collect` policy and delete the application, the order of garbage collect is: `test3 -> test2 -> test1`.
+
+```yaml
+apiVersion: core.oam.dev/v1beta1
+kind: Application
+metadata:
+  name: gc-dependency
+  namespace: default
+spec:
+  components:
+  - name: test1
+    type: webservice
+    properties:
+      image: crccheck/hello-world
+      port: 8000
+    dependsOn:
+      - "test2"
+  - name: test2
+    type: webservice
+    properties:
+      image: crccheck/hello-world
+      port: 8000
+    inputs:
+      - from: test3-output
+        parameterKey: test
+  - name: test3
+    type: webservice
+    properties:
+      image: crccheck/hello-world
+      port: 8000
+    outputs:
+      - name: test3-output
+        valueFrom: output.metadata.name
+  
+  policies:
+    - name: gc-dependency
+      type: garbage-collect
+      properties:
+        order: dependency
+```