patch 9.0.2076: Vim9: No support for type aliases

Problem:  Vim9: No support for type aliases
Solution: Implement :type command

A type definition is giving a name to a type specification.  This also known
type alias.

	:type ListOfStrings = list<string>

The type alias can be used wherever a built-in type can be used.  The type
alias name must start with an upper case character.

closes: #13407

Signed-off-by: Christian Brabandt <cb@256bit.org>
Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
diff --git a/src/viminfo.c b/src/viminfo.c
index d328156..58bf419 100644
--- a/src/viminfo.c
+++ b/src/viminfo.c
@@ -1374,7 +1374,8 @@
 		    case VAR_INSTR:
 		    case VAR_CLASS:
 		    case VAR_OBJECT:
-				     continue;
+		    case VAR_TYPEALIAS:
+				      continue;
 		}
 		fprintf(fp, "!%s\t%s\t", this_var->di_key, s);
 		if (this_var->di_tv.v_type == VAR_BOOL