[IMPLEMENT][iOS] Custom cast receiver support

[Jmilham21]

Description

Custom Chromecast receivers are now supported for DRM via iOS 4.19.0. This mirrors the Android issue; coordinate if the assignee on that ticket is already working.

Acceptance Criteria

• Add to the props list to match the userInfo field now available for PlaylistItem
• Update the index.js and index.d.ts to match above
• Parse the userInfo prop in Swift and add to the player builder
• Test that your custom data is being sent to your custom receiver (if you take this ticket, tag @jwplayer/team_sdks for assistance if you are unsure how)

Requirements

• 4.19.0 must be implemented as described here
• Documentation to match this (if you take this ticket, tag @jwplayer/team_sdks for assistance)