Feature Request: Add option for relative import

It would be great if this package can change our absolute imports to relative imports.

Example 1
`import 'package:my_app/lib/src/foo.dart'`
to
`import 'foo.dart'`

Example 2
```
import 'package:my_app/lib/src/p1/foo.dart'
import 'package:my_app/lib/src/p2/foo.dart'
```
to
```
import 'p1/foo.dart'
import 'p2/foo.dart'
```
**if imported in `src`**
to
```
import '../p1/foo.dart'
import 'foo.dart'
```
**if imported in `p2`**

I would like to contribute to this feature but can anyone guide me with this?

The issue names no files, tests, or entry points. Start by locating the package's import conversion logic and existing option tests, then clarify how relative paths and the requested option should be represented. Done means the examples are transformed correctly from each importing directory and covered by tests.

Written by the indexing model from the issue text.