Scheduler: Refactor resource data accessor and grouping

[Ambrozy]

No description provided.

[wdevfx]

The OnContentReady behavior changed when we have a local resource data source
Previously, because the local resources data source load was sync -> on the OnContentReady hook resources was already applied

Now it always work like remote data source (see attached video)
Let's try to wait the resources initial loading (if exists) before firing the OnContentReady event

Screen.Recording.2568-05-27.at.10.36.59.mov

Clicked wrong button while pushing comments, sorry :)

[wdevfx]

Unfortunately, found the broken case
If Scheduler has groups, and we change the resources option synchronously after component creation -> appointments will not be loaded

Configuration:

const resourceA = {
  fieldExpr: 'resourceId',
  dataSource: [{
    text: 'A',
    id: 1,
    color: '#1e90ff',
  }],
};
const resourceB = {
  fieldExpr: 'resourceId',
  dataSource: [{
    text: 'B',
    id: 1,
    color: '#f00',
  }],
};
 const appointment = {
  startDate: '2024-01-01T01:00:00',
  endDate: '2024-01-01T02:00:00',
  text: 'Test appt',
  resourceId: 1,
}

const scheduler = $('#scheduler').dxScheduler({
  dataSource: [appointment],
  views: [{
    type: 'workWeek',
    name: 'TestView',
  }],
  currentView: 'TestView',
  currentDate: '2024-01-01',
  groups: ['resourceId'],
  resources: [resourceA],
}).dxScheduler('instance');

// Change resources synchronously
scheduler.option('resources', [resourceB]);

In the previous `24.2``` version, this case works well (but with a remote DataSource, we will receive the internal error in both versions)

I checked other similar cases (like similar runtime groups change, change resources without groups and etc.),
Looks like other cases works similarly

[wdevfx]

[🚨 Important]

Discussed and decided to get rid of this waitAsync in terms of a separate tech task

It's better to use the sinon.fakeTimers instead of the real marco tasks