fix: ignore import path transformations on win32 platform

The current version of the library throws me a bunch of errors, when trying to build my nest application with transformer-plugin enabled.

In general, the plugin works fine when DTOs are simple enough. But in cases, when classes have complex properties represented by other classes defined elsewhere. In such cases, the application doesn't start as the plugin breaks all such imports

Errors state, that:

ERROR in ../../libs/shared/src/models/dto/user.dto.ts 29:41-155
Module not found: Error: Can't resolve '../H:\projects\myproject\libs\shared\src\models\dto\client-user.dto' in 'H:\projects\myproject\libs\shared\src\models\dto'
****

Which means, it replaces the short relative path (originally import { ClientDto } from './client.dto';) with a long absolute path starting with ../.

Don't know, why you use path.posix.relative and not just path.relative, but however, for the best compatibility possible, I made the if statement to skip all these path transformations when running on a windows environment.

Briefly tested on one of my projects, and this little change fixed me 75 errors, and none of the mappings broke.

P.S. The second commit was created only to pass the sonar verification. Didn't change it to the recommended '??' for backward compatibility, as I'm not ready to properly test the related functionality

P.S.S. @nartc appreciate if you check and merge it ASAP as I really like your package architecturally wise, but it's the only thing that blocks me from running some of my projects natively on my windows laptop.

nartc / mapper

fix: ignore import path transformations on win32 platform #570