feat(clangd): enable the LazyVim clangd extra

C and C++ only had Treesitter highlighting. The extra adds clangd,
clangd_extensions.nvim, the cpp parser and a codelldb debug config;
lazy-lock.json pins clangd_extensions.nvim.

lazy-lock.json

@@ -7,6 +7,7 @@
   "blink.compat": { "branch": "main", "commit": "2ed6d9a28b07fa6f3bface818470605f8896408c" },
   "bufferline.nvim": { "branch": "main", "commit": "655133c3b4c3e5e05ec549b9f8cc2894ac6f51b3" },
   "catppuccin": { "branch": "main", "commit": "edefef779ab08ce1a4a404713e3012b0d202bd35" },
+  "clangd_extensions.nvim": { "branch": "main", "commit": "78c2ecd659d54972be17aa6ba2deac3c53223b80" },
   "cmp-bazel": { "branch": "main", "commit": "68b45f8d341e8783b3c08285a5b02cbf38e43547" },
   "conform.nvim": { "branch": "master", "commit": "016802de402556da54c36bd7359b441266b01cdd" },
   "crates.nvim": { "branch": "main", "commit": "7039bc1d130e424232a7aa64ceddb170a154ff5b" },

lazyvim.json

@@ -1,6 +1,7 @@
 {
   "extras": [
     "lazyvim.plugins.extras.lang.astro",
+    "lazyvim.plugins.extras.lang.clangd",
     "lazyvim.plugins.extras.lang.docker",
     "lazyvim.plugins.extras.lang.dotnet",
     "lazyvim.plugins.extras.lang.git",