vim-patch:9.1.0304: filetype: cgdb config file is not recognized (#28294)

Problem:  filetype: cgdb config file is not recognized
Solution: Detect cgdbrc files as cgdbrc filetype
          (Wu, Zhenyu)

closes: vim/vim#14458

1492fe6903

Co-authored-by: Wu, Zhenyu <wuzhenyu@ustc.edu>

runtime/lua/vim/filetype.lua

@@ -1289,6 +1289,7 @@ local filename = {
   ['/etc/default/cdrdao'] = 'cdrdaoconf',
   ['/etc/defaults/cdrdao'] = 'cdrdaoconf',
   ['cfengine.conf'] = 'cfengine',
+  cgdbrc = 'cgdbrc',
   ['CMakeLists.txt'] = 'cmake',
   ['.alias'] = detect.csh,
   ['.cshrc'] = detect.csh,