console.lua: use terminal_display_width when picking longest menu item

Previously this function would just count bytes which was very easily
broken by incantations like `Ő̶̧͍̹͔̮̮̦͌̈̌̂́̊͜K͖̮̼̯͖͆͋̓̀̕` which take up 52 bytes while being just
2 normal width characters visually.

`terminal_display_width` correctly counts `Ő̶̧͍̹͔̮̮̦͌̈̌̂́̊͜K͖̮̼̯͖͆͋̓̀̕` as 2 visual characters.

Note: GitHub strips all these in their web UI but there are many Unicode
combining characters after each letter of the `OK`s above that produce
a "cursed" text effect.

Fixes #17772

player/lua/console.lua

@@ -348,9 +348,12 @@ local function calculate_max_item_width()
     end
 
     local longest_item = prompt .. ("a"):rep(9)
+    local longest_item_width = utils.terminal_display_width(longest_item)
     for _, item in pairs(selectable_items) do
-        if #item > #longest_item then
+        local item_width = utils.terminal_display_width(item)
+        if item_width > longest_item_width then
             longest_item = item
+            longest_item_width = item_width
         end
     end
 

player/lua/context_menu.lua

@@ -15,6 +15,7 @@ You should have received a copy of the GNU Lesser General Public
 License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
 ]]
 
+local utils = require "mp.utils"
 local assdraw = require "mp.assdraw"
 
 local options = {
@@ -157,9 +158,12 @@ local function calculate_width(menu_items, osd_w, osd_h, checkbox)
     end
 
     local longest = ""
+    local longest_width = 0
     for _, title in pairs(titles) do
-        if #title > #longest then
+        local title_width = utils.terminal_display_width(title)
+        if title_width > longest_width then
             longest = title
+            longest_width = title_width
         end
     end