vim-patch:9.0.1350: CPON files are not recognized (#22392)

Problem:    CPON files are not recognized.
Solution:   Add patterns for CPON files. (Amaan Qureshi, closes vim/vim#12053)

c2254764bc

Co-authored-by: Amaan Qureshi <amaanq12@gmail.com>

runtime/lua/vim/filetype.lua

@@ -242,6 +242,7 @@ local extension = {
   csh = function(path, bufnr)
     return require('vim.filetype.detect').csh(path, bufnr)
   end,
+  cpon = 'cpon',
   moc = 'cpp',
   hh = 'cpp',
   tlh = 'cpp',