Downloaded episodes from podcasts you're not subscribed to are not being displayed in "Downloaded" filter

### Description

Related with this previous report: https://github.com/Automattic/pocket-casts-android/issues/715
I'd let you decide if it's a duplicate or not.
IMHO showing all downloaded podcasts ignoring subscription status should be the default, addition of subscription state for filters is a nice-to-have. I considered filling this as a bug for that reason (plus, it can lead to storage being filled and users having no knowledge on how to get it back without removing everything)

Steps to reproduce:
1. Go to discover page
2. Download any episode from a podcast you're not subscribed to
3. Go to "Downloaded" filter, the episode isn't there

### Screenshots or screen recording

_No response_

### Did you search for existing list?

- [x] I have searched for existing issues.

Reproduce the issue by downloading an episode from Discover for an unsubscribed podcast, then opening the Downloaded filter. Trace the Downloaded filter's handling of subscription status and confirm that the episode appears there without requiring a subscription.

Written by the indexing model from the issue text.