Fixes to array associations and enum

• Join on array associations were broken on rails 5.2.3 or higher
• Improve enum builder to use similar tools as the Interval, which use generated strings
• Fix array set scopes to properly cast the values while querying
• Add setting to raise an exception (or just notify) whenever the enum will build a method on top of an existing one
• Add additional scopes has_ and has_any_ for enum sets
• Add ability to get the enum values as symbols using Enum::Roles.keys or Model.roles_keys