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>
diff --git a/runtime/doc/vim9class.txt b/runtime/doc/vim9class.txt
index a68b97c..c68288a 100644
--- a/runtime/doc/vim9class.txt
+++ b/runtime/doc/vim9class.txt
@@ -423,6 +423,12 @@
 define a function with the same name and different type of arguments.
 
 
+Member Initialization ~
+If the type of a member is not explicitly specified in a class, then it is set
+to "any" during class definition.  When an object is instantiated from the
+class, then the type of the member is set.
+
+
 Extending a class ~
 							*extends*
 A class can extend one other class. *E1352* *E1353* *E1354*