Move user struct to own file, under Invidious namespace

src/invidious/user/user.cr

@@ -0,0 +1,27 @@
+require "db"
+
+struct Invidious::User
+  include DB::Serializable
+
+  property updated : Time
+  property notifications : Array(String)
+  property subscriptions : Array(String)
+  property email : String
+
+  @[DB::Field(converter: Invidious::User::PreferencesConverter)]
+  property preferences : Preferences
+  property password : String?
+  property token : String
+  property watched : Array(String)
+  property feed_needs_update : Bool?
+
+  module PreferencesConverter
+    def self.from_rs(rs)
+      begin
+        Preferences.from_json(rs.read(String))
+      rescue ex
+        Preferences.from_json("{}")
+      end
+    end
+  end
+end