fix: runner encoding paths incorrectly on windows

[harry774]

Description

When passed target parameter for main_qa.dart file it does encode incorrectly

On fluttium_example123_launcher.dart file it shows import 'package:AppName/C:\Users\name\source\repo\.\main_qa.dart' as app

Expected Behavior

It should encode path of given target file correctly as

On fluttium_example123_launcher.dart file import 'package:AppName/lib/main_qa.dart' as app

Screenshots

[wolfenrain]

Thanks for the issue! It seems to be regression of a previous problem I have seen on Windows. Will need to fix that in the codegen.