Moved Cronet code under Connectivity

$ cp -r Cronet/ Connectivity/
$ rm -r Cronet/*

Bug: 251054736
Test: atest CronetApiTest
Change-Id: I25d5238fe530ffaa830ce64c67b351d40b8030ea
CTS-Coverage-Bug: 251012627
diff --git a/Cronet/TEST_MAPPING b/Cronet/TEST_MAPPING
new file mode 100644
index 0000000..815d496
--- /dev/null
+++ b/Cronet/TEST_MAPPING
@@ -0,0 +1,7 @@
+{
+  "postsubmit": [
+    {
+      "name": "CronetApiTest"
+    }
+  ]
+}