plugins: use new config-aware mkMappingOption

Generated using:

- `sd -F "inherit (lib.nvim.binds) mkMappingOption;" "inherit (config.vim.lib) mkMappingOption;" $(find . -type f)`
- `sd -F "{lib, ...}: let" "{config, lib, ...}: let" $(find . -type f)`

Tweaked manually (placement in inherit list, fixing todo-comments and toggleterm).

Ran `nix run nixpkgs#deadnix -- -e` to clean up.
Next commit includes unrelated dead code.

modules/plugins/assistant/chatgpt/chatgpt.nix

@@ -1,7 +1,11 @@
-{lib, ...}: let
+{
+  config,
+  lib,
+  ...
+}: let
   inherit (lib.options) mkEnableOption;
-  inherit (lib.nvim.binds) mkMappingOption;
   inherit (lib.nvim.types) mkPluginSetupOption;
+  inherit (config.vim.lib) mkMappingOption;
 in {
   options.vim.assistant.chatgpt = {
     enable = mkEnableOption "ChatGPT AI assistant. Requires the environment variable OPENAI_API_KEY to be set";