cxx-qt-gen: remove generation of wrapper for emitting signals

[ahayzen-kdab]

This is now unused as the type conversion has been removed.

Requires #554
Requires #571

[ahayzen-kdab]

This doesn't work yet as we have two different cases for inheriting signals

• inherit a signal from the base class
• inherit a signal as a property has generated it

For the first we need to generate a connect + emit method, the second we need to generate a connect method but no emit as the qproperty has done this already.

    #[cxx_qt::qsignals(CustomBaseClass)]
    pub enum Signals<'a> {
        /// Inherit the DataChanged signal from the QAbstractListModel base class
        #[inherit]
        DataChanged {
            /// Top left affected index
            top_left: &'a QModelIndex,
            /// Bottom right affected index
            bottom_right: &'a QModelIndex,
            /// Roles that have been modified
            roles: &'a QVector_i32,
        },
    }

    #[cxx_qt::qsignals(RustSignals)]
    pub enum Connection<'a> {
        // Example of using #[inherit] so that connections to the logging_enabled property can be made
        #[inherit]
        // We don't ever emit this enum, so silence clippy warnings
        #[allow(dead_code)]
        /// The Q_SIGNAL emitted when the Q_PROPERTY logging_enabled changes
        LoggingEnabledChanged,
    }

[ahayzen-kdab]

This will be solved by the new API as in that when there is a qproperty a myPropertyChanged signal will be generated and the connect method. So we don't have the enum craziness.

[ahayzen-kdab]

Requires #571

[ahayzen-kdab]

This now works and ready for review :-)

[LeonMatthesKDAB]

LGTM, always good to see things simplified.