Update PeerTube API for video-playlists to include/exclude local Playlists

[mblomdahl]

When listing videos, we can pass the query param ?isLocal=true to filter out federated videos. See API docs here: https://docs.joinpeertube.org/api-rest-reference.html#tag/Video/operation/getVideos

For implementing OwnTube-tv/web-client#138, it would be beneficial include only local videos on the PeerTube server-side, instead of filtering client-side. Can we please update the root-level GET /api/v1/video-playlists API endpoint to support passing the same isLocal filter as for videos?