Fetch 100 releases when importing a record

The release group contains only 25 releases, which breaks tracking
scrobble status. Albums like "Toto IV" or "Hounds of Love" end up
looking like they're not part of the collections because the individual
releases are not stored.

Still error prone, because this change doesn't paginate to more than 100
records, but that will be addressed in a future commit.

lib/music_brainz/api_impl.ex

@@ -287,6 +287,14 @@ defmodule MusicBrainz.APIImpl do
     json_get(url, config)
   end
 
+  @impl true
+  def get_releases(release_group_id, config) do
+    url =
+      "https://musicbrainz.org/ws/2/release?fmt=json&limit=100&release-group=#{release_group_id}"
+
+    json_get(url, config)
+  end
+
   @doc """
   Uses the [search](https://musicbrainz.org/doc/MusicBrainz_API/Search#Release_Group) endpoint with a search query string.