modules/lsp/keymaps: init

Initial LSP keymaps option, inspired by `keymapsOnEvent` and
`plugins.lsp.keymaps`.

Users can define `lspBufAction` instead of `action` if they wish to use
a `vim.lsp.buf.<action>` callback.

modules/lsp/default.nix

@@ -137,6 +137,10 @@ in
     };
   };
 
+  imports = [
+    ./keymaps.nix
+  ];
+
   config =
     let
       enabledServers = lib.pipe cfg.servers [