Any formatter capable of taking key sequence or a key stroke and converting
it into a string. These formatters are used to produce the strings that the
user sees in the keys preference page and the menus, as well as the strings
that are used for persistent storage.
Formats an individual key into a human readable format. This uses an
internationalization resource bundle to look up the key. This does not
do any platform-specific formatting (e.g., Carbon's command character).
key - The key to format; must not be null.
The key formatted as a string; should not be null.