console.lua: don't convert integers for mp.input to string

I misunderstood CogentRedTester's review in
https://github.com/mpv-player/mpv/pull/10282#discussion_r1428972352 as
referring to the cursor_position in mp.input's arguments instead of the
one received by the closed callback.

The cursor_position passed to input.get doesn't need to be converted to
a number because it was already JSON, while the cursor_position received
by the closed callback is currently a string, and we need to pass JSON
in input-event script messages to keep it as an integer to work around
mpv converting integer script message arguments to string.

This is more noticeable after implementing mp.input.select(): its submit
argument currently receives the selected index as a string, and this
makes Lua error if you use it as an index of a numerical table, e.g.:

submit = function (id)
    mp.set_property(property, tracks[tonumber(id)].selected and "no"
                              or tracks[tonumber(id)].id)
    ...
end,

This commit avoids having to call tonumber(id).

.luacheckrc

@@ -63,7 +63,8 @@ local mp_globals = {
             set_mouse_area = {},
             set_osd_ass = {},
         }
-    }
+    },
+    unpack = {},
 }
 
 local mp_internal = {