Activation: initially support psu update

Initial support for PSU update by starting a systemd unit with PSU
inventory path and image dir as arguments.

Add an example psu-update@.service that shows how the arguments are
passed to systemd unit and expanded to command line arguments.

Tested: Upload a dummy tarball, create a dummy service that only prints
        the arguments, and verify the service is invoked correctly when
        the RequestedActivation is set to Active.

Signed-off-by: Lei YU <mine260309@gmail.com>
Change-Id: I7e122f1cce234caf4951d3e3daad5bee406b507b
diff --git a/test/meson.build b/test/meson.build
index 4ec6c0e..0b7b217 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -37,12 +37,13 @@
     ssl,
   ])
 
-test_item_updater = executable(
-  'test_item_updater',
+test_phosphor_psu_manager = executable(
+  'test_phosphor_psu_manager',
   '../src/activation.cpp',
   '../src/item_updater.cpp',
   '../src/version.cpp',
   'test_item_updater.cpp',
+  'test_activation.cpp',
   include_directories: [psu_inc, test_inc],
   link_args: dynamic_linker,
   build_rpath: oe_sdk.enabled() ? rpath : '',
@@ -56,4 +57,4 @@
   ])
 
 test('util', test_util)
-test('item_updater', test_item_updater)
+test('phosphor_psu_manager', test_phosphor_psu_manager)