[Feature Request]: Syncing subscriptions with Piped

### Guidelines

- [X] I have searched the issue tracker for [open](https://github.com/FreeTubeApp/FreeTube/issues?q=is%3Aopen+is%3Aissue) and [closed](https://github.com/FreeTubeApp/FreeTube/issues?q=is%3Aissue+is%3Aclosed) issues that are similar to the feature request I want to file, without success.
- [X] I have searched the [documentation](https://docs.freetubeapp.io/) for information that matches the description of the feature request I want to file, without success.
- [X] This issue contains only one feature request.

### Problem Description

One of the key features that is missing in the freetube GitHub repository is the ability to sync subscriptions from a user's piped account into the app. Currently, users have to manually enter and manage their subscriptions within the app, which can be time-consuming and inconvenient for those who already have a well-curated list of subscriptions on piped.

### Proposed Solution

The addition of support to sync subscriptions from a piped account would enhance the user experience of freetube. Users would be able to easily import and synchronize their existing subscriptions from piped, saving them time and effort. This would provide a seamless transition for users who are already comfortable managing their subscriptions on piped and make it more convenient for them to continue using freetube.

### Alternatives Considered

While manual subscription management is currently possible in freetube, it does not offer a smooth way for users to migrate their existing subscriptions from piped.

### Issue Labels

ease of use improvement, new feature, new optional setting, support for external software

### Additional Information

[Piped](https://github.com/TeamPiped/Piped)