Rename PluginInstanceManager to PluginActionManager. am: 08d1a77825 am: 4082801b5b

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/15558876

Change-Id: I2d13d08a16d7383a518be1cee61a67a30ca12ce2