feat: add preference to set default trending page

Closes https://git.nadeko.net/Fijxu/invidious/issues/212

Enjoy xCbl6YaK4PEX6d9g6m26YMdHJtQgJ

src/invidious/routes/feeds.cr

@@ -1,6 +1,13 @@
 {% skip_file if flag?(:api_only) %}
 
 module Invidious::Routes::Feeds
+  enum TrendingTypes
+    Default
+    Music
+    Gaming
+    Movies
+  end
+
   def self.view_all_playlists_redirect(env)
     env.redirect "/feed/playlists"
   end
@@ -44,13 +51,14 @@ module Invidious::Routes::Feeds
   end
 
   def self.trending(env)
-    locale = env.get("preferences").as(Preferences).locale
+    preferences = env.get("preferences").as(Preferences)
+    locale = preferences.locale
 
     trending_type = env.params.query["type"]?
-    trending_type ||= "Default"
+    trending_type ||= preferences.default_trending_type.to_s
 
     region = env.params.query["region"]?
-    region ||= env.get("preferences").as(Preferences).region
+    region ||= preferences.region
 
     begin
       trending, plid = fetch_trending(trending_type, region, locale)

src/invidious/routes/preferences.cr

@@ -168,6 +168,9 @@ module Invidious::Routes::PreferencesRoute
       delete.reverse_each { |i| hidden_channels.delete_at(i) }
     end
 
+    default_trending_type = env.params.body["default_trending_type"]?.try &.as(String)
+    default_trending_type ||= Invidious::Routes::Feeds::TrendingTypes::Default
+
     # Convert to JSON and back again to take advantage of converters used for compatibility
     preferences = Preferences.from_json({
       annotations:                 annotations,
@@ -205,6 +208,7 @@ module Invidious::Routes::PreferencesRoute
       show_nick:                   show_nick,
       save_player_pos:             save_player_pos,
       hidden_channels:             hidden_channels,
+      default_trending_type:       default_trending_type,
     }.to_json)
 
     if user = env.get? "user"