patch 8.2.0200: Vim9 script commands not sufficiently tested

Problem:    Vim9 script commands not sufficiently tested.
Solution:   Add more tests.  Fix storing global variable.  Make script
            variables work.
diff --git a/src/proto/evalvars.pro b/src/proto/evalvars.pro
index 1d557f5..ff2f58f 100644
--- a/src/proto/evalvars.pro
+++ b/src/proto/evalvars.pro
@@ -33,6 +33,7 @@
 void set_vim_var_nr(int idx, varnumber_T val);
 char *get_vim_var_name(int idx);
 typval_T *get_vim_var_tv(int idx);
+int set_vim_var_tv(int idx, typval_T *tv);
 varnumber_T get_vim_var_nr(int idx);
 char_u *get_vim_var_str(int idx);
 list_T *get_vim_var_list(int idx);