Add helper library to get remotely provisioned key

The code is mostly from credstore. The intention here is that we replace
that code with a common library.

Test: librkp_support_test
Change-Id: I28ebc5a253c037277dad6d39b761b4e8aa4347e8
diff --git a/provisioner/support/TEST_MAPPING b/provisioner/support/TEST_MAPPING
new file mode 100644
index 0000000..fc30104
--- /dev/null
+++ b/provisioner/support/TEST_MAPPING
@@ -0,0 +1,7 @@
+{
+  "presubmit": [
+    {
+      "name": "librkp_support_test"
+    }
+  ]
+}