"Free Preview" label should show up on Liturgies screen, rather than individual liturgy items

[brettdh]

Motivation

Design: https://projects.invisionapp.com/d/main?origin=v7#/console/12356801/259676365/preview

Unlike meditation categories and podcasts, liturgies are entire units, rather than just being collections of items. This is evident in other ways the app presents liturgies - with a larger "album art" view, and in the way that liturgies are (were) released all at once, rather than item by item. Per the design above, if there is a liturgy that's marked as a free preview, this should show up on the collection view. This will save non-patron users frustration when searching around to find what items they can actually listen to now.

This should probably apply to other categories as well. Here's an attempt at a general rule:

If any collection (podcast, meditation category, or liturgy) contains items that the active user cannot access, it should be labeled thusly:

• The padlock icon should a ppear on the series tile
• If there is at least one "Free Preview" item, the "Free Preview" label should also show up on the series tile
• If there are no free preview items, the padlock item should still appear, and the series tile should not be dimmed (see below)

Scope

Writing this issue sparked some related questions, which we're now tracking in #200. The implementations coming from those conversations are out of scope here; this is just to match the design for the Liturgies screen.