Incorrect critical path

[arcady-zherdev]

Reported here: https://forum.bryntum.com/viewtopic.php?f=52&t=27833

Happens when having two levels of manually scheduled tasks:

{
    "id": 1,
    "name": "Planisware",
    "startDate": "2022-12-25",
    "endDate": "2022-12-31",
    "duration": 5,
    "expanded": true,
    "manuallyScheduled": true,
    "children": [
        {
            "id": 2,
            "name": "Overall Project Management",
            "startDate": "2022-12-26",
            "endDate": "2022-12-31",
            "duration": 4,
            "manuallyScheduled": true
        }
    ]
}

In this case ProjectModel calculates its earlyEndDate incorrectly (uses 2nd level child value only)..

Initial progress is pushed to 8435-critical-path branch.