Conditional multi bind

[guobingkun]

Reopen of druid-io/druid-api#76
A follow up PR of #2682

Usage example:

       ConditionalMultibind.create(props, binder, Animal.class)
                           .conditionBinder("animal.type", Predicates.equalTo("cat"), Cat.class)
                           .conditionBinder("animal.type", Predicates.equalTo("dog"), Dog.class);

At binding time, this will check the value set for property "animal.type" in props. If the value is "cat", it will
add a binding to Cat.class. If the value is "dog", it will add a binding to Dog.class.

At ingestion time, you will get the items that satisfy their corresponding predicates by calling
injector.getInstance(Key.get(new TypeLiteral<Set<Animal>>(){}))

[drcrallen]

👍

[fjy]

👍