Return a version of the given string, where for every
star (*) in the string the star and the chars immediately to its left and right
are gone. So "ab*cd" yields "ad" and "ab**cd" also yields "ad".
starOut("ab*cd") → "ad"
starOut("ab**cd") → "ad"
starOut("sm*eilly") → "silly"
public String starOut(String str)
{
}