Add Ironic standalone tests

This patch adds the following standalone tests:

  * agent_ipmitool + wholedisk image + bios
  * agent_ipmitool + partitioned image + bios
  * pxe_ipmitool + wholedisk image + bios
  * pxe_ipmitool + partitioned image + bios

Partial-Bug: #1660606

Change-Id: Ic04b0f134e20d9937a610a14d7c4128f45738eeb
diff --git a/ironic_tempest_plugin/services/baremetal/base.py b/ironic_tempest_plugin/services/baremetal/base.py
index ec572b2..bb9ba9e 100644
--- a/ironic_tempest_plugin/services/baremetal/base.py
+++ b/ironic_tempest_plugin/services/baremetal/base.py
@@ -18,9 +18,21 @@
 from tempest.lib.common import api_version_utils
 from tempest.lib.common import rest_client
 
+# NOTE(vsaienko): concurrent tests work because they are launched in
+# separate processes so global variables are not shared among them.
 BAREMETAL_MICROVERSION = None
 
 
+def set_baremetal_api_microversion(baremetal_microversion):
+    global BAREMETAL_MICROVERSION
+    BAREMETAL_MICROVERSION = baremetal_microversion
+
+
+def reset_baremetal_api_microversion():
+    global BAREMETAL_MICROVERSION
+    BAREMETAL_MICROVERSION = None
+
+
 def handle_errors(f):
     """A decorator that allows to ignore certain types of errors."""