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).

player/lua/input.lua

@@ -19,9 +19,10 @@ local utils = require "mp.utils"
 local input = {}
 
 local function register_event_handler(t)
-    mp.register_script_message("input-event", function (type, text, cursor_position)
+    mp.register_script_message("input-event", function (type, args)
         if t[type] then
-            local suggestions, completion_start_position = t[type](text, cursor_position)
+            local suggestions, completion_start_position =
+                t[type](unpack(utils.parse_json(args or "") or {}))
 
             if type == "complete" and suggestions then
                 mp.commandv("script-message-to", "console", "complete",