MudExpansionPanel: Use ParameterState, remove obsolete API and change to async API

[ScarletKuro]

Description

Fixes: #8429

Breaking Changes:

Remove IsInitiallyExpanded

It's not necessary anymore.
You can either set a constant

<MudExpansionPanels MultiExpansion>
    <MudExpansionPanel Class="panel-one" Text="Panel One" IsExpanded="true">
        ...
    </MudExpansionPanel>
</MudExpansionPanels>

StateHasChanged will not reset on re-render back to constant because we avoided writing to the Parameter https://learn.microsoft.com/en-us/aspnet/core/blazor/components/overwriting-parameters?view=aspnetcore-8.0

or you can use two way binding.

<MudExpansionPanels MultiExpansion>
    <MudExpansionPanel Class="panel-one" Text="Panel One" @bind-IsExpanded="_isExpanded">
        ...
    </MudExpansionPanel>
</MudExpansionPanels>

@code
{
    private bool _isExpanded = true;
}

To set the initial expansion.

Change API to be async.

This component was firing EventCallbacks in a fire-and-forget manner. We changed all the API to be async.

Simplify code

We do not need _collapseIsExpanded variable or updateParent arguments, since the ParamterState manages the state correctly, therefore everything can be done in a more simple way.

How Has This Been Tested?

Visual, current unit tests, new unit test.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• The PR is submitted to the correct branch (dev).
• My code follows the code style of this project.
• I've added relevant tests.

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 88.86%. Comparing base (61e8a76) to head (027833e).

Files	Patch %	Lines
...mponents/ExpansionPanel/MudExpansionPanel.razor.cs	81.81%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #8446      +/-   ##
==========================================
+ Coverage   88.84%   88.86%   +0.01%     
==========================================
  Files         416      416              
  Lines       12358    12307      -51     
  Branches     2458     2447      -11     
==========================================
- Hits        10980    10937      -43     
+ Misses        845      836       -9     
- Partials      533      534       +1     

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[henon]

I don't understand why we need the IExpansionPanelManager interface at all. Why not simply use internal methods like before? If I understand correctly, this change doesn't concern the users at all as the interface is internal anyway.

[henon]

Using only IsExpandedChanged is considered invalid now.

If you only care about getting notifications I think this should still be valid usage?

[ScarletKuro]

I don't understand why we need the IExpansionPanelManager interface at all. Why not simply use internal methods like before? If I understand correctly, this change doesn't concern the users at all as the interface is internal anyway.

True 😂 I just saw it was using event so I automatically put an interface because I got this observer-observable pattern in my head, I will change that.

[ScarletKuro]

If you only care about getting notifications I think this should still be valid usage?

It will not work currently if you just subscribe only to IsExpandedChanged and do not update the IsExpanded, it will not collapse or expand (depending on the initial IsExpanded). At first I thought everything is working as intended and it only worked because we modified IsExpanded directly and when i set it in the component this effect disappeared, but now after debugging I realised it's a ParamterState framework bug 😤. I know how to fix it, but I need to come up with integration tests since we didnt catch this bug before and it's not something you can unit tests as you need the re-renders etc.

[ScarletKuro]

Fixed: #8457
Rebased this branch, reverted the example with just IsExpandedChanged, and changed the PR description.
I removed the IsExpandedChanged moment in the #8447
Not making public the ParamterState for now was a good idea.