Better name generation for nested resources in ResourceLeakFixer

[andrecsilva]

After the transformation by ResourceLeakFixer, the following example will result in:

public void nestedReaders() throws IOException {
  BufferedReader br = new BufferedReader(new BufferedReader(new FileReader("~/test.txt")));
}

  public void nestedReaders() throws IOException {
    try (FileReader resource1 = new FileReader("~/test.txt");
    BufferedReader resource = new BufferedReader(resource1);
    BufferedReader br = new BufferedReader(resource)) {
    }
  }

The resource1 name is a poor choice and can be improved.