Function expand_dollar_with_args

* Expand a string that follows '$' * * For example, if the input string is * ($(FOO)$($(BAR)))$(BAZ) * this helper evaluates * $($(FOO)$($(BAR))) * and returns a new string containing the expansion (note that the string is * recursively expanded), also advancing 'str' to point to the next character * after the corresponding closing parenthesis, in this case, *str will be * $(B