Thought about this when reviewing #6747.

## warnings

### EMPTY_IMPORT_META

\```text
[EMPTY_IMPORT_META] Warning: `import.meta` is not available with the `iife` output format and will be empty.
   ╭─[ main.js:1:13 ]
   │
 1 │ console.log(import.meta.hello);
   │             ─────┬─────  
   │                  ╰─────── You need to set the output format to `esm` for `import.meta` to work correctly.
───╯

\```

• "import.meta is not available with the iife output format " is bit of confusing. Should be something like: "Your output format. iife might run into errors when having import.mets". Also point out that import.meta will be replaced with {} due to so.
• iife format will enable inlineDynamicImports by default, while esm doesn't. Helper message should point out how to achieve the same result.
• If users want to continue on iffe format, help message doesn't provide workaround solution for solving this warning. Should point out that, to remove the warning, users could use transform.define to replace import.meta with {} explicitly if they want to continue using iife format