Merge "Pass main executor to PluginInstanceManager.Factory." into sc-v2-dev am: 9847a6a75b am: 685338f7c6

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/15558874

Change-Id: I20cf971bd58253cb7e50da22fe411571fdcd711d