Feature Request: Fast Seek Scrubber Scrollbar

### The User Problem:
A user will want to interact and discover the back catalogue of any given podcast. They attempt to do so by navigating the default view:

Podcasts>Select Specific podcast>Podcast detail page.

From here, they are able to search for a specific podcast, or apply various sort orders.

However, if any given podcast has hundreds of episodes, it's quite cumbersome to scroll to a specific area for selection purposes.

_**How might we allow toolbar interactivity to allow for faster seeking and scrubbing?**_

### The Idea

Instead of the scroll bar being temporal and non-interactable, allow users to use the scroll indicator as a touch target, and allow users to scroll quickly through the list. Apple Music has an example of this, but should not be used as a benchmark since their right aligned scrollbar allows for alphabetical selection, which might not make sense for Pocket Casts' purposes.

Start at the Podcasts > Select Specific podcast > Podcast detail page flow and review how its episode list and current scrollbar behave. Define the intended touch interaction and validate it against podcasts with hundreds of episodes; done means users can seek and scrub through the episode list faster without relying on ordinary scrolling.

Written by the indexing model from the issue text.