Add setting to control auto-downloads on follow

[SergioEstevao]

| 📘 Part of: #2284 |
|:---:|

Fixes #

This PR updates the AutoDownload settings to explicit say if auto-downloads on follow are active or not.
It also separate the number of downloads on subscribe from the auto-download new episode limits.
It always be two episode downloaded.

To test

1. Start the app
2. Go to Profile -> Downloads -> Auto-Download Settings
3. Check if you have the option New Episodes enabled, if not enable it
4. Check if you see the option On Follow
5. Enable the switch
6. Go to Discovery and find a podcast you don't follow
7. Subscribe to it
8. Check if you see a maximum of auto-downloads, depending on the limit set, happening for the podcast
9. Go back to Profile -> Downloads -> Auto-Download Settings
10. This time disable On Follow
11. Go to Discovery and find a podcast you don't follow
12. Subscribe to it
13. Check if you don't see auto-downloads happening for the podcast

Checklist

• I have considered if this change warrants user-facing release notes and have added them to CHANGELOG.md if necessary.
• I have considered adding unit tests for my changes.
• I have updated (or requested that someone edit) the spreadsheet to reflect any new or changed analytics.

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 7.78. The due date for this milestone has already passed. Please assign it to a milestone with a later deadline or check whether the release for this milestone has already been finished.

Generated by 🚫 Danger

[danielebogo]

It works correctly!