Make validation_resources a stable interface

Move the module to tempest.lib, add unit tests, release notes and
update imports.

Change-Id: I76b3b8e9a83bd83a6b5742b6d2ceb84642f653ad
diff --git a/releasenotes/notes/add-validation-resources-to-lib-dc2600c4324ca4d7.yaml b/releasenotes/notes/add-validation-resources-to-lib-dc2600c4324ca4d7.yaml
new file mode 100644
index 0000000..7814f4e
--- /dev/null
+++ b/releasenotes/notes/add-validation-resources-to-lib-dc2600c4324ca4d7.yaml
@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    Add the `validation_resources` module to tempest.lib. The module provides
+    a set of helpers that can be used to provision and cleanup all the
+    resources required to perform ping / ssh tests against a virtual machine:
+    a keypair, a security group with targeted rules and a floating IP.