vim-patch:9.0.1281: Cadence files are not recognized (#22130)

Problem:    Cadence files are not recognized.
Solution:   Recognize Cadence files. (Janez Podhostnik, closes vim/vim#11951)

cb626a4692

Co-authored-by: Janez Podhostnik <janez.podhostnik@gmail.com>

runtime/lua/vim/filetype.lua

@@ -191,6 +191,7 @@ local extension = {
   qc = 'c',
   cabal = 'cabal',
   capnp = 'capnp',
+  cdc = 'cdc',
   cdl = 'cdl',
   toc = 'cdrtoc',
   cfc = 'cf',