feat: WindowOptions for macOS

[l0uisgrange]

Adding new WindowOptions for macOS

#[derive(Debug, Clone, Default)]
pub(crate) struct PlatformSpecificInitialWindowAttrs {
    pub(crate) titlebar_hidden: bool,
    pub(crate) title_hidden: bool,
    pub(crate) fullsize_content_view: bool,
    pub(crate) titlebar_transparent: bool,
    pub(crate) movable_by_window_background: bool,
}

I'm not sure about moving some to reactive window attributes... what do you think?

[l0uisgrange]

The last CI is failing, but does not seem to be the PR's fault