patch 9.0.1988: Vim9: potential use-after-free for class members

patch 9.0.1988: Vim9: potential use-after-free for class members

Problem:  Vim9: potential use-after-free for class members
Solution: Use the class-related grow array for storing the
          member type instead of using a temporary type
          list grow array

Use the type list grow array associated with the class than using a
temporary type list grow array to allocate the class member type.

For simple types, a predefined type is used. For complex types, the type
is dynamically allocated from a grow array. For class variables, the
type grow array in the class should be used. So that the lifetime of the
type is same as the lifetime of the class.

closes: #13279

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>