Inhibit Idle when window is maximized

[skr4n]

Currently, the application inhibits idle only for full-screen mode.
It would be helpful to have this when the window is maximized as well.

Closes #1609

[camelCaseNick]

I would highly suggest also checking for this.is_active() and notify::is-active, because otherwise when Foliate is maximised in the background, e.g. on a different workspace or behind a different window, it will still inhibit the session.

[skr4n]

I would highly suggest also checking for this.is_active() and notify::is-active, because otherwise when Foliate is maximised in the background, e.g. on a different workspace or behind a different window, it will still inhibit the session.

Fixed. Thanks for pointing it out.

[LibMeow2025]

can this be merged please? @johnfactotum