[Java] Fix #1012 DTO char array setter visibility.

Previously, the setter was generated as package-private rather than
public.

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/java/JavaDtoGenerator.java

@@ -1359,7 +1359,7 @@ private void generateArrayProperty(
 
             classBuilder.appendPublic().append("\n")
                 .append(generateDocumentation(indent, fieldToken))
-                .append(indent).append("void ").append(formattedPropertyName)
+                .append(indent).append("public void ").append(formattedPropertyName)
                 .append("(").append(typeName).append(" value)\n")
                 .append(indent).append("{\n")
                 .append(indent).append(INDENT).append(validateMethod).append("(value);\n")