feat(neovim): switch to null-ls

- switch from diagnostic-languageserver to null-ls.nvim
- add shellcheck & shfmt
- replace nix-linter with statix
- replace prettier with prettier_d_slim
- add stylelint, eslint_d & prettier_d_slim binaries

home/editors/neovim/lsp/mappings.lua

@@ -23,7 +23,8 @@ wk.register({
   },
   f = {
     function()
-      vim.lsp.buf.formatting_seq_sync(nil, nil, { "tsserver", "diagnosticls" })
+      -- TODO switch to `vim.lsp.buf.format` after updating to nvim 0.8
+      vim.lsp.buf.formatting_seq_sync(nil, nil, { "tsserver", "null-ls" })
     end,
     "Format file",
   },