patch 9.0.1780: Vim9 type not defined during object creation

patch 9.0.1780: Vim9 type not defined during object creation

Problem:  Vim9 type not defined during object creation
Solution: Define type during object creation and not during class
          definition, parse mulit-line member initializers, fix lock
          initialization

If type is not specified for a member, set it during object creation
instead of during class definition.  Add a runtime type check for the
object member initialization expression

Also, while at it, when copying an object or class, make sure the lock
is correctly initialized.

And finally, parse multi-line member initializers correctly.

closes: #11957
closes: #12868
closes: #12869
closes: #12881

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