feat(nvim): add lsp signature plugin

modules/programs/nvim/plugins/default.nix

@@ -131,6 +131,7 @@ with builtins;
       event = [ "BufRead" "BufNewFile" ];
       conf = readFile ./nvim-lspconfig.lua;
       dependencies = [
+        { plugin = lsp_signature-nvim; }
         {
           plugin = null-ls-nvim;
           conf = readFile ./null-ls-nvim.lua;

modules/programs/nvim/plugins/nvim-lspconfig.lua

@@ -96,6 +96,13 @@ local on_attach_def = function(client, bufnr)
       vim.lsp.inlay_hint(bufnr, true)
     end, timeout)
   end
+
+  require("lsp_signature").on_attach({
+    bind = true, -- This is mandatory, otherwise border config won't get registered.
+    handler_opts = {
+      border = "rounded",
+    },
+  }, bufnr)
 end
 
 local lspconfig_default_options = {