Add ability to load different properties for on page chage

[kieraneglin]

I'm designing a multi-page/window GUI. To clean up my code, I'd like to pass properties from different files on page change.

For example:

1. You start the app and main.rs calls upon main.qml.
2. You click the button Show Users.
3. users.qml is loaded with variables provided by users.rs.

etc. I want to create a 1:1 mapping of views and "controllers".

I'd love to see this ability in the future! I'm completely new to Rust and Qt Quick, so if this isn't part of the spec just let me know.