Multiselect: pTemplate="selectedItems" layout is empty on first render using Reactive forms

[rostislavcz]

Describe the bug

Without custom template:

Screen.Recording.2023-12-22.at.17.40.10.mov

With custom template:

Screen.Recording.2023-12-22.at.17.40.34.mov

When using reactive form and custom template:
<ng-template let-items pTemplate="selectedItems">
On first render, items are undefined, but this is not rerendered when default values in formControl are set

In my opinion if I look to https://github.com/primefaces/primeng/blob/master/src/app/components/multiselect/multiselect.ts

Constructor part sets selectedOption property, but it seems that it is undefined at first call but, probably right after first render value changes, but there is set onPush strategy, so template won't redraw as it should

How to fix? Didnt tried, but probably this is very similar to dropdown:

So something like this should fix the problem
`

    constructor(public el: ElementRef, public renderer: Renderer2, public cd: ChangeDetectorRef, public zone: NgZone, public filterService: FilterService, public config: PrimeNGConfig, public overlayService: OverlayService) {
            effect(() => {
                const modelValue = this.modelValue();
    
                const visibleOptions = this.visibleOptions();
                if (visibleOptions && ObjectUtils.isNotEmpty(visibleOptions) && modelValue) {
                    if (this.optionValue && this.optionLabel) {
                        this.selectedOptions = visibleOptions.filter((option) => modelValue.includes(option[this.optionLabel]) || modelValue.includes(option[this.optionValue]));
                    } else {
                        this.selectedOptions = [...modelValue];
                    }
                    // ADD THIS!!!
                   this.cd.markForCheck();
                }
            });
        }

`

Environment

This bug will be in any environment

Reproducer

No response

Angular version

17.0.5

PrimeNG version

17.2.0

Build / Runtime

Angular CLI App

Language

TypeScript

Node version (for AoT issues node --version)

18.0.6

Browser(s)

all

Steps to reproduce the behavior

No response

Expected behavior

No response