[Feature Request]: polyfill `import.meta`

### What problem does this feature solve?

https://github.com/rolldown/tsdown/issues/370#issuecomment-3088926309

- convert `import.meta` to {} in cjs format
- giving a warning if user source code has `import.meta` in cjs format

At least we should finish task two

### What does the proposed API look like?

n/a