nvim: Add support for clangd for C++ and ccls for C

clangd doesn't work the way I want it to with C.
ccls doesn't work the way I want it to with C++.

So now I use both for each ones they work well with.

modules/packages/nvim.nix

@@ -21,6 +21,7 @@
         (llvmPackages_19.clang-tools.override {
           enableLibcxx = true;
         })
+        ccls
         ripgrep
         nil
         gcc14