patch 8.2.2975: Vim9: can only use an autoload function name as a string

Problem:    Vim9: can only use an autoload function name as a string.
Solution:   Load the autoload script when encountered. (closes #8124)
diff --git a/src/evalvars.c b/src/evalvars.c
index 7581a14..cd1f170 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -2921,8 +2921,9 @@
 	if (ht != NULL)
 	    return ht;				// local variable
 
-	// in Vim9 script items at the script level are script-local
-	if (in_vim9script())
+	// In Vim9 script items at the script level are script-local, except
+	// for autoload names.
+	if (in_vim9script() && vim_strchr(name, AUTOLOAD_CHAR) == NULL)
 	{
 	    ht = get_script_local_ht();
 	    if (ht != NULL)