Move the v2 api_sample functional tests

This patch move the all v2.1 api sample tests under
'functional/api_sample_tests'. Also move sample files under
'doc/api-samples'.

Co-Authored-By: Ed Leafe <ed@leafe.com>
Co-Authored-By: Alex Xu <hejie.xu@intel.com>
Partial-Bug: #1462901
Change-Id: I2b924f2ad7687a23a018a9b658e8acd9e04d7963

doc/api_samples/os-server-groups/server-groups-get-resp.json

@@ -0,0 +1,9 @@
+{
+    "server_group": {
+        "id": "5bbcc3c4-1da2-4437-a48a-66f15b1b13f9",
+        "name": "test",
+        "policies": ["anti-affinity"],
+        "members": [],
+        "metadata": {}
+    }
+}

doc/api_samples/os-server-groups/server-groups-list-resp.json

@@ -0,0 +1,11 @@
+{
+    "server_groups": [
+        {
+            "id": "616fb98f-46ca-475e-917e-2563e5a8cd19",
+            "name": "test",
+            "policies": ["anti-affinity"],
+            "members": [],
+            "metadata": {}
+        }
+    ]
+}

doc/api_samples/os-server-groups/server-groups-post-req.json

@@ -0,0 +1,6 @@
+{
+    "server_group": {
+        "name": "test",
+        "policies": ["anti-affinity"]
+    }
+}

doc/api_samples/os-server-groups/server-groups-post-resp.json

@@ -0,0 +1,9 @@
+{
+    "server_group": {
+        "id": "5bbcc3c4-1da2-4437-a48a-66f15b1b13f9",
+        "name": "test",
+        "policies": ["anti-affinity"],
+        "members": [],
+        "metadata": {}
+    }
+}