patch 8.2.3028: GUI mouse events not tested

Problem:    GUI mouse events not tested.
Solution:   Add test_gui_mouse_event().  Add mouse tests. Also add a few
            viminfo tests. (Yegappan Lakshmanan, closes #8407)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index fdcc00f..f8af8ef 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -1696,6 +1696,8 @@
 			ret_void,	    f_test_garbagecollect_soon},
     {"test_getvalue",	1, 1, FEARG_1,	    NULL,
 			ret_number,	    f_test_getvalue},
+    {"test_gui_mouse_event",	5, 5, 0,	    NULL,
+			ret_void,	    f_test_gui_mouse_event},
     {"test_ignore_error", 1, 1, FEARG_1,    NULL,
 			ret_void,	    f_test_ignore_error},
     {"test_null_blob",	0, 0, 0,	    NULL,