Made RubyString#dumpCommon19 a static method.
Moved dumpCommon19 and necessary tr-related methods and classes to StringSupport.
Removed unused arguments and changed return types to not use JRuby core classes.
[Truffle] Initial implementation of String#count.
[Truffle] Handle some error cases in String#count.
[Truffle] Support method_missing on primitive types via auto-boxing.
[Truffle] Handle more failure cases in String#count.