The key attribute is not being properly propagated and applied to importedElements

[Archmonger]

Discussed in #1270

^{Originally posted by shawncrawley February 10, 2025}
I could not get GridLayout to work as a dynamically loaded component. After digging into the issue, I found that it was because the children of a GridLayout must have the key attribute, but it is not being found on the children when constructing the GridLayout object on the client side. I am clearly passing it in on the Python side, as seen in my example below, so it is getting dropped/lost somewhere.

return GridLayout(
    Props(
        className="layout",
        layout=layout,
        cols=12,
        rowHeight=30,
        width=1200,
    ),
    lib.html.div(Props(key="a"), "a"),
    lib.html.div(Props(key="b"), "b"),
    lib.html.div(Props(key="c"), "c")
)