Listenbrainz scrobbling (#1424)

* Refactor session_keys to its own package

* Adjust play_tracker

- Don't send external NowPlaying/Scrobble for tracks with unknown artist
- Continue to the next agent on error

* Implement ListenBrainz Agent and Auth Router

* Implement frontend for ListenBrainz linking

* Update listenBrainzRequest

- Don't marshal Player to json
- Rename Track to Title

* Return ErrRetryLater on ListenBrainz server errors

* Add tests for listenBrainzAgent

* Add tests for ListenBrainz Client

* Adjust ListenBrainzTokenDialog to handle errors better

* Refactor listenbrainz.formatListen and listenBrainzRequest structs

* Refactor agent auth_routers

* Refactor session_keys to agents package

* Add test for listenBrainzResponse

* Add tests for ListenBrainz auth_router

* Update ListenBrainzTokenDialog and auth_router

* Adjust player scrobble toggle

ui/src/reducers/dialogReducer.js

@@ -5,6 +5,8 @@ import {
   DUPLICATE_SONG_WARNING_CLOSE,
   EXTENDED_INFO_OPEN,
   EXTENDED_INFO_CLOSE,
+  LISTENBRAINZ_TOKEN_OPEN,
+  LISTENBRAINZ_TOKEN_CLOSE,
 } from '../actions'
 
 export const addToPlaylistDialogReducer = (
@@ -61,3 +63,26 @@ export const expandInfoDialogReducer = (
       return previousState
   }
 }
+
+export const listenBrainzTokenDialogReducer = (
+  previousState = {
+    open: false,
+  },
+  payload
+) => {
+  const { type } = payload
+  switch (type) {
+    case LISTENBRAINZ_TOKEN_OPEN:
+      return {
+        ...previousState,
+        open: true,
+      }
+    case LISTENBRAINZ_TOKEN_CLOSE:
+      return {
+        ...previousState,
+        open: false,
+      }
+    default:
+      return previousState
+  }
+}