Add a blur option to the main background

[jrunestone]

First off thanks for this theme :)

I'd appreciate the option of applying the blur to my main background at all times. And maybe the blur radius?

I don't know anything about QML but I guess a simple ternary check here is sufficient? https://github.com/surajmandalcell/Elegant-sddm/blob/master/Elegant/Main.qml#L52

State {
    name: "stateLogin"
    PropertyChanges { target: loginFrame; opacity: 1}
    PropertyChanges { target: powerFrame; opacity: 0}
    PropertyChanges { target: sessionFrame; opacity: 0}
    PropertyChanges { target: userFrame; opacity: 0}
    PropertyChanges { target: bgBlur; radius: 0} // config.blur_login ? config.blur_radius : 0
}