Merge branch 'playlist-embed' into 'develop'

api/config/spa_urls.py

api/funkwhale_api/music/serializers.py

api/funkwhale_api/music/spa_views.py

api/tests/music/test_spa_views.py

api/tests/music/test_views.py

changes/changelog.d/playlist-embed.enhancement

front/src/EmbedFrame.vue

front/src/components/audio/EmbedWizard.vue

front/src/views/playlists/Detail.vue