Allow open detection

[Robert-M-Lucas]

Objective

Currently, there appears to be no way to tell if the console is open. This is an almost required feature for a console as without it you cannot block inputs while using the console or control how the mouse behaves when the console is open.

Solution

• Exposed the ConsoleUiState struct (keeping the fields as only crate public)
• Exposed a function that returns whether the console is currently open

Imagined usage

(with the console only conditionally included in the project)

fn keyboard_update(
    ...,
    #[cfg(debug_assertions)]
    console: Res<ConsoleUiState>
) {
    #[cfg(debug_assertions)]
    if console.open() {
        return;
    }

    ...
}

I can also see this being useful for locking and unlocking the mouse based on whether the console is visible.

Other

There also appears to be a text_focus field however this appears to not be updated while the console is
presented. In the future, it'd be nice to have an text_focused() method so that an open console only blocks
input when the text field is selected.

[doonv]

Looks good!