conform: autoformat on save only for specified filetypes

Enable the autoformat on save only for specified filetypes.
By default this is only for lua, similar as LSP is by default
only enabled for lua. Based on conform recipe:
https://github.com/stevearc/conform.nvim/blob/master/doc/recipes.md

Author: dam9000

init.lua

@@ -608,10 +608,16 @@ require('lazy').setup({
     'stevearc/conform.nvim',
     opts = {
       notify_on_error = false,
-      format_on_save = {
-        timeout_ms = 500,
-        lsp_fallback = true,
-      },
+      format_on_save = function(bufnr)
+        -- Enable format on save for specified filetypes
+        local enable_filetypes = { 'lua' }
+        if vim.tbl_contains(enable_filetypes, vim.bo[bufnr].filetype) then
+          return {
+            timeout_ms = 500,
+            lsp_fallback = true,
+          }
+        end
+      end,
       formatters_by_ft = {
         lua = { 'stylua' },
         -- Conform can also run multiple formatters sequentially