In order to support in article fundraising and other announcements, surveys, etc, we'd like to add the ability to specify where in the app announcements should be displayed.

Currently announcements appear only as a feed card in the Explore feed on the apps. In many cases it is useful to show announcements in the article reader context instead.

To support this concept in a backwards compatible way the announcements response will have an additional field "placement" added to it. By default the placement will be "feed", while the other initial supported value will be "article". If the placement field is absent the client should assume "feed" as the value. Older clients who do not have support for this parameter will continue to show the announcements only in the feed, ignoring the new parameter. Newer clients should use this parameter to determine the user experience for the announcement. See subtasks for client user experience for the new "article" placement.

Regardless of the placement value the same business logic should be used for an announcement: one time display limit, expiration times, dismissal logic, etc, should all be identical across placements.

See subtasks for client user experience for the new "article" placement.