RubySet#newSet should be a static method instead of an instance method

[caleb]

JRuby 9.2.16.0

The newSet method of org.jruby.ext.set.RubySet should be a static method so that users can create sets from Java:

jruby/core/src/main/java/org/jruby/ext/set/RubySet.java

Lines 129 to 133 in 87bb5cc

	RubySet newSet(final Ruby runtime) {
	RubySet set = new RubySet(runtime, getMetaClass());
	set.allocHash(runtime);
	return set;
	}