eventEdit items config should not be of type Array

[chuckn0rris]

Forum post

According to our docs, items config for eventEdit feature may be specified as object and as an array: https://bryntum.com/docs/scheduler/#Scheduler/feature/base/EditBase#config-items
In case it was specified as array, it replaces all fields in EventEditor and an error occurred in the console.
Update the docs with the info about replacing all fields if used an array notation.
Add tests.

Try this config that may be used with our basic example:

eventEdit : {
        items : [{
            type    : 'number',
            name    : 'hours',
            label   : 'Hours',
            weight   : 1,
            dataset : { }
        }],
    },

Error text:

RecurringEventEdit.js:93 Uncaught (in promise) TypeError: Cannot set property 'menu' of undefined
    at EventEdit.onEditorConstructed (RecurringEventEdit.js:93)
    at EventEdit.getEditor (EventEdit.js:546)
    at EventEdit.internalShowEditor (EventEdit.js:621)
    at EventEdit.doEditEvent (EventEdit.js:757)
    at EventEdit.editEvent (EventEdit.js:727)
    at Scheduler.internalAddEvent (SchedulerBase.js:536)
    at Scheduler.onSchedulerDblClick (SchedulerBase.js:369)
    at Scheduler.trigger (Events.js:1057)
    at Scheduler.handleScheduleEvent (TimelineDomEvents.js:127)
    at HTMLDivElement.handler (EventHelper.js:510)