Handle potentially aliased imports

[kevmoo]

It's really not safe to reference Map or String in the case where someone does import "dart:core" as foo; – in practice this should be rare.

Same for other types. In general, we just write out the type name w/ out worrying about imports.

[pavanpodila]

This is also an issue where the same class name collides with others from the std library or Flutter. Eg. I have an Action class that needs an import alias else it collides with the Action in Flutter SDK.

[Rexios80]

I just added support for library prefixes to hive_ce: https://github.com/IO-Design-Team/hive_ce/blob/3a322857b8bfc6ed2ae98001e26d7576cb7a42ee/hive_generator/lib/src/class_builder.dart#L225

Would that be a reasonable solution here as well?