Card in sidebar doesn't support full screen

[rickhelmus]

Hello,

When placing a card inside a sidebar, the full screen functionality doesn't seem to work as expected, and the card will only expand to the dimensions of the sidebar.

Small example:

bslib::page_fillable(
    bslib::layout_sidebar(
        sidebar = bslib::sidebar(
            title = "Test",
            bslib::card("Side card", full_screen = TRUE)
        ),
        bslib::card("Main card", full_screen = TRUE),
    )
)

Tested with version 0.6.1 and with the latest code from GitHub.

Thanks, Rick