feat: add music artists

tests/snapshots/youtube__music_album_only_singles.snap

@@ -0,0 +1,33 @@
+---
+source: tests/youtube.rs
+expression: artist
+---
+MusicArtist(
+  id: "UCfwCE5VhPMGxNPFxtVv7lRw",
+  name: "Sulli",
+  header_image: "[header_image]",
+  description: "Choi Jin-ri, better known by her stage name Sulli, was a South Korean actress and singer. She first made her debut as a child actress, appearing as a supporting cast member on the SBS historical drama Ballad of Seodong. Following this, she earned a number of guest roles, appearing in the television series Love Needs a Miracle and Drama City, and the film Vacation. She then subsequently appeared in the independent films Punch Lady and BA:BO, the former being her first time cast in a substantial dramatic role.\nAfter signing a record deal with SM Entertainment, Sulli rose to prominence as a member of the girl group f(x) formed in 2009. The group achieved both critical and commercial success, with four Korean number-one singles and international recognition after becoming the first K-pop act to perform at SXSW. Concurrently with her music career, Sulli returned to acting by starring in the SBS romantic comedy series, To the Beautiful You, a Korean adaptation of the shōjo manga Hana-Kimi where her performance was positively received and earned her two SBS Drama Awards and a nomination at the 49th Paeksang Arts Awards.\n\nFrom Wikipedia (https://en.wikipedia.org/wiki/Sulli) under Creative Commons Attribution CC-BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/legalcode)",
+  wikipedia_url: Some("https://en.wikipedia.org/wiki/Sulli"),
+  subscriber_count: "[subscriber_count]",
+  tracks: "[tracks]",
+  albums: [
+    AlbumItem(
+      id: "MPREb_vq8dZfFBEdx",
+      name: "고블린 Goblin",
+      cover: "[cover]",
+      artists: [
+        ArtistId(
+          id: Some("UCfwCE5VhPMGxNPFxtVv7lRw"),
+          name: "Sulli",
+        ),
+      ],
+      album_type: Single,
+      year: Some(2019),
+      by_va: false,
+    ),
+  ],
+  playlists: "[playlists]",
+  similar_artists: "[artists]",
+  tracks_playlist_id: None,
+  videos_playlist_id: Some("OLAK5uy_lmH3iVq6lqjsnLkBWzpvRTh0DidLzbU-I"),
+)