Add option to control autoplay behavior for Watch Later playlist

[bsdf]

This PR introduces a new setting to control how autoplay behaves for videos in the "Watch Later" playlist.

Motivation:

Currently, the app always treats the "Watch Later" list as a playlist for autoplay. When one video from the list ends, the next one in the list automatically begins.

For users who use "Watch Later" as a temporary list for individual videos, the expected behavior is to see standard video suggestions after a video finishes, not to automatically play through the entire list.

Proposed Change:

• A new setting, "Autoplay treats Watch Later as a playlist" is added under Settings > Player > Misc.
• This setting is enabled by default to ensure the existing behavior remains unchanged for current users.
• When a user disables this setting, watching a video from "Watch Later" will be followed by standard suggestions instead of the next video in the playlist.

This change offers more flexibility, allowing users to tailor the app's behavior to their preferred workflow.

Let me know what you think