Made moving/transferring playlists possible

src/lib/components/inputs/SelectField.svelte

src/lib/server/models/Playlist.ts

...utes/(leader)/playlists/[id=integer]/edit/+page.server.js

src/routes/(leader)/playlists/[id=integer]/edit/+page.svelte

src/routes/(leader)/playlists/create/+page.svelte