Define a default set of "LinkType" provided with a fresh installation

Django Admin should provide a default set of link types.

Link types are used for show descriptions and timeslot notes.

Suggestions are:

• Name: Website, type: type.link.website
• Name: CBA, type: type.link.cba
• Name: Freie Radios Online, type: type.link.freie-radios-online
• Name: Funkwhale, type: type.link.funkwhale
• Name: Mixcloud, type: type.link.mixcloud
• Name: Soundcloud, type: type.link.soundcloud
• Name: Internet Archive (archive.org), type: type.link.internet-archive
• Name: YouTube, type: type.link.youtube
• Name: Spotify, type: type.link.spotify
• Name: Instagram, type: type.link.instagram
• Name: Facebook, type: type.link.facebook

Note, the given Name is only used for administrative purposes, or as a fallback. The actual names could be provided client-site (Dashboard, Website) only and translated different languages using i18n, where applicable.