vim-patch:9.0.1455: C++ 20 modules are not recognized (#23124)

Problem:    C++ 20 modules are not recognized.
Solution:   Add patterns to recognize C++ 20 modules as "cpp". (Ben Jackson,
            closes vim/vim#12261)

732d69e191

Co-authored-by: Ben Jackson <puremourning@gmail.com>

runtime/lua/vim/filetype.lua

@@ -257,6 +257,10 @@ local extension = {
   tcc = 'cpp',
   hxx = 'cpp',
   hpp = 'cpp',
+  ccm = 'cpp',
+  cppm = 'cpp',
+  cxxm = 'cpp',
+  ['c++m'] = 'cpp',
   cpp = function(path, bufnr)
     return vim.g.cynlib_syntax_for_cpp and 'cynlib' or 'cpp'
   end,