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/git/gitsigns/gitsigns.nix

@@ -5,8 +5,8 @@
 }: let
   inherit (lib.options) mkEnableOption;
   inherit (lib.modules) mkRenamedOptionModule;
-  inherit (lib.nvim.binds) mkMappingOption;
   inherit (lib.nvim.types) mkPluginSetupOption;
+  inherit (config.vim.lib) mkMappingOption;
 in {
   imports = [
     (mkRenamedOptionModule ["vim" "git" "gitsigns" "codeActions" "vim" "gitsigns" "codeActions"] ["vim" "git" "gitsigns" "codeActions" "enable"])