Set Initial Active Element in Playlist Context

[joncameron]

Description

Avalon should be able to parse a positional parameter in a playlist URL, like /playlists/19?position=3. When the application returns this route, it should key on the position parameter and set the active playlist item to be the third in the list. To do this, Ramp needs to a property to read from so that it knows which playlist item to initially set as active.
The original issue report is #5514.

Done Looks Like

• Ramp can read homepage attribute in the manifest and use the link in the presentation context in the structured navigation
• Ramp uses this value instead of the previously used manifest/canvas route so Ramp knows where to go (different link for each playlist item)
• Playlist route URLs with position parameter return the playlist view page with the specified playlist item active (one-based numbering) (2-3 points in Ramp)