wifi(API): Send directed broadcast post connection for suggestions

Based on feedback received, moving away from using a PendingIntent for
post connection action (PendingIntent's are impossible to persist &
maybe too heavy for our use-case). We'll now send out a simple directed
broadcast to the app that added the network suggestion.

Also, added annotation indicating the permission requirement for using
the new API.

Bug: 115504887
Test: make api-stubs-docs-update-current-api -j128
Change-Id: Ide169b139ca16d43bd250de4d0447807d85a60ed