vim-patch:partial:8.1.1939: code for handling v: variables in generic eval file (#35968)

Problem:    Code for handling v: variables in generic eval file.
Solution:   Move v: variables to evalvars.c. (Yegappan Lakshmanan,
            closes vim/vim#4872)

e5cdf153bc

Remove direct reference to "vimvars" for following functions:
- assert_error()
- get_vim_var_nr()
- get_vim_var_list()
- get_vim_var_dict()
- get_vim_var_str()
- set_cmdarg()
- set_reg_var()
- set_vcount()
- set_vexception()
- set_vthrowpoint()
- set_vim_var_bool()
- set_vim_var_dict()
- set_vim_var_list()
- set_vim_var_nr()
- set_vim_var_special()
- set_vim_var_string()
- set_vim_var_type()

Reorder functions based on v8.2.4930 for
eval_one_expr_in_str() and eval_all_expr_in_str().

Co-authored-by: Bram Moolenaar <Bram@vim.org>

src/nvim/memline.c

@@ -56,8 +56,8 @@
 #include "nvim/change.h"
 #include "nvim/cursor.h"
 #include "nvim/drawscreen.h"
-#include "nvim/eval.h"
 #include "nvim/eval/typval.h"
+#include "nvim/eval/vars.h"
 #include "nvim/ex_cmds_defs.h"
 #include "nvim/fileio.h"
 #include "nvim/getchar.h"