Configure watcher tempest's microversion in devstack

Adds a tempest configuration for min and max microversions supported
by watcher. This help us to define the correct range of microversion
to be tested on each stable branch.
New microversion proposals should also increase the default
max_microversion, in order to work with watcher-tempest-plugin
microversion testing.

Change-Id: I0b695ba4530eb89ed17b3935b87e938cadec84cc
(cherry picked from commit adfe3858aa)
(cherry picked from commit defd3953d8)
Signed-off-by: Douglas Viroel <viroel@gmail.com>

devstack/plugin.sh

@@ -38,6 +38,9 @@ if is_service_enabled watcher-api watcher-decision-engine watcher-applier; then
         # Start the watcher components
         echo_summary "Starting watcher"
         start_watcher
+    elif [[ "$1" == "stack" && "$2" == "test-config" ]]; then
+        echo_summary "Configuring tempest for watcher"
+        configure_tempest_for_watcher
     fi
 
     if [[ "$1" == "unstack" ]]; then