ldid: added formula (1.1.2)

This should fix #28216 and #25586. Added the ldid code-signing program for iOS by Saurik.
Can a test be added to do something more substantial than e.g. `--version` or `--help`? See `cmake.rb` for an example of an application formula with a good test and `tinyxml2.rb` for an example of a library formula with a good test. Thanks!