fix: OnParameterSet should not set internal value when multiple is enabled in ListComponentBase

[Tyme-Bleyaert]

🐛 Bug Report

When setting a custom collection yourself with FluentSelect and multiple enabled, the collection gets overriden because of the internal value of single select gets set.

💻 Repro or Code Sample

<FluentSelect TOption="Issues" Multiple="true" Items="_allIssues" SelectedOptions="FlagsAsEnumerable" SelectedOptionsChanged="OnSelectionChanged">
    <OptionTemplate>
            @context.ToString()
    </OptionTemplate>
</FluentSelect>

@code{
    private Issues _issues;

    [Parameter]
    public Issues Values { get; set; }

    [Parameter]
    public EventCallback<Issues> ValuesChanged { get; set; }

    [Flags]
    public enum Issues 
    {
        NoIssues = 0,
        FullyBroken = NoIssues << 1,
        SettingsMissing = FullyBroken << 1,
        MaintenanceNeeded = SettingsMissing << 1,

    }
    private readonly static Issues[] _allIssues = Enum.GetValues<Issues>();

    protected override void OnParametersSet()
    {
        _issues = Values;
        base.OnParametersSet();
    }

    protected IEnumerable<Issues> FlagsAsEnumerable
    {
        get
        {
            if (_issues == Issues.NoIssues)
                return [Issues.NoIssues];

            if (_issues == Issues.FullyBroken)
                return [Issues.FullyBroken];

            return _allIssues.Where(e => _issues.HasFlag(e) && e != Issues.NoIssues && e != Issues.FullyBroken);
        }
    }

    private Task OnSelectionChanged(IEnumerable<Issues> issues)
    {
        if (issues.Contains(IssueTypes.None) && _issues != Issues.NoIssues)
            _issues = Issues.NoIssues;
        else if (issues.Contains(IssueTypes.Defect) && _issues != Issues.FullyBroken)
            _issues = Issues.FullyBroken;
        else
            _issues = issues.Aggregate(default(Issues), (a, b) => a |= b);

        return ValuesChanged.InvokeAsync(_issues);
    }
}

🤔 Expected Behavior

I can choose the selected values and ListComponentBase should not override them.

😯 Current Behavior

The values changed gets raised before the new values are set.

💁 Possible Solution

🔦 Context

The component does not work correctly in its current state.

🌍 Your Environment