[Fixes #2349] Support for JDK 14

Added the ability to parse and pretty-print the new 'x instanceof String y' pattern concept.
Added a test to the pretty printer to confirm that it works.

test/pretty/resource/before/PatternInstanceOf.java

@@ -0,0 +1,8 @@
+// version 14:
+public class PatternInstanceOf {
+	public void foo(Object o) {
+		if (o instanceof String y) {
+			System.out.println(y);
+		}
+	}
+}