The following changes are proposed for the iptables proxier:

* There are three places where a string specifying IP:port is parsed
  using something like this:

      if index := strings.Index(e.endpoint, ":"); index != -1 {

  This will fail for IPv6 since V6 addresses contain colons. Also,
  the V6 address is expected to be surrounded by square brackets
  (i.e. []:). Fix this by replacing call to Index with
  call to LastIndex() and stripping out square brackets.
* The String() method for the localPort struct should put square brackets
  around IPv6 addresses.
* The logging in the merge() method for proxyServiceMap should put brackets
  around IPv6 addresses.
* There are several places where filterRules destination is hardcoded to
  /32. This should be a /128 for IPv6 case.
* Add IPv6 unit test cases

fixes #48550