controller.Component: add support for string based listeners when dynamically adding components

Right now, the model.Component implementation is a bit more advanced.

Inside Neo.examples.model.advanced.MainContainerController we have the method:

    onAddButtonTextfieldButtonClick(data) {
        let me = this;

        me.getReference('content-container').insert(2, {
            items: [{
                ntype     : 'textfield',
                flex      : 'none',
                labelText : 'data.button2Text:',
                labelWidth: 150,
                width     : 300,

                bind: {
                    value: '${data.button3Text}'
                },

                listeners: {
                    change: me.onTextField3Change,
                    scope : me
                }
            }]
        });
    }

It would be nice if we can optionally specify it the same way as inside the MainContainer view as well:

    onAddButtonTextfieldButtonClick(data) {
        let me = this;

        me.getReference('content-container').insert(2, {
            items: [{
                ntype     : 'textfield',
                flex      : 'none',
                labelText : 'data.button2Text:',
                labelWidth: 150,
                width     : 300,

                bind: {
                    value: '${data.button3Text}'
                },

                listeners: {
                    change: 'onTextField3Change'
                }
            }]
        });
    }