feat: locate msix assets path from script file directory if necessary

[lijy91]

When I depend on msix in another package, the msix assets path cannot be obtained when calling create. I added the logic to find the package config from the directory where the script file is located.

List<String> arguments = [];
// ...
await Msix(arguments).create();

https://github.com/leanflutter/flutter_distributor/blob/a112f0a82cf10041f856154415dcb5e0de1d2c89/packages/flutter_app_packager/lib/src/makers/msix/app_package_maker_msix.dart#L59

[YehudaKremer]

Hello

I will try to test and approve this PR in the next day

Thank you

[YehudaKremer]

LGTM 👍

Available in version 3.13.1

Thank you @lijy91