Auth Strategies (#1257)

* auth strategies

* default to no auth

* rename base auth strategy

* rename base strategy cont.

* refactor auth strategy methods and LocalAuth

* activate old session options even if is falsy value

* move restartOnAuthFail to LegacyAuthStrategy option

* add link to guide item

* update example/shell

* types

index.js

@@ -21,5 +21,11 @@ module.exports = {
     ProductMetadata: require('./src/structures/ProductMetadata'),
     List: require('./src/structures/List'),
     Buttons: require('./src/structures/Buttons'),
+    
+    // Auth Strategies
+    NoAuth: require('./src/authStrategies/NoAuth'),
+    LocalAuth: require('./src/authStrategies/LocalAuth'),
+    LegacySessionAuth: require('./src/authStrategies/LegacySessionAuth'),
+    
     ...Constants
 };