fix: skip file header comment in .dart file.

[iliYF]

Unable to fix the import path if there is a file header comment in .dart file such as:

/// This is file header comment
///
///
import 'package:xxx/yyy/z.dart'

[adnanjpg]

Some files may start with // and not ///, a common case for this is the 'ignore for file' cases. Please check out #49