Change Export style when using peertube subscription

[Oymate]

Checklist

• [x] I checked, but didn't find any duplicates (open OR closed) of this issue in the repo.
• [x] I have read the contribution guidelines given at https://github.com/TeamNewPipe/NewPipe/blob/HEAD/.github/CONTRIBUTING.md.
• [x] This issue contains only one feature request. I will open one issue for every feature I want to request.

Describe the feature you want

When peertube subscription are done, and exports taken youtube and peertube is compiled into one list. It would be nice if these services had option to be separately exported.

Is your feature request related to a problem? Please describe it

It is a bit conflicting for other apps(freetube) when subscribing to PT channels, to import this backup.

Additional context

How will you/everyone benefit from this feature?

People can easily get different backup for different services.

*ALSO, This feature will help us colonize the galaxy!

[opusforlife2]

In other words, you wish to have either:

1. A separate export option per service in the Subscriptions tab, or
2. Separate files for each service's subscription export when using the Export button.

[Oymate]

Yup