ParameterState: Fix when subscribing only to EventCallback

[ScarletKuro]

Description

This fixes an interesting problem when you subscribe only to EventCallback and modify the child, for example you have content collapsed and you want to expand it via public method like ToggleAsync, the content would not expand, when it should.

This problem was found here: #8446

Consider this as example:

<MudExpansionPanels>
	<MudExpansionPanel Text="Panel with async loaded contents" MaxHeight="1000" IsExpandedChanged="ExpandedChanged">
		Secret content
	</MudExpansionPanel>
</MudExpansionPanels>

@code {
    private void ExpandedChanged(bool newVal)
    {   
    }
}

Note that when you click on expansion, you are triggering inner child toggle method

Before

After

The line in unit tests that specifically tests that this moment is covered:

MudBlazor/src/MudBlazor.UnitTests/State/ParameterStateUsageTests.cs

Line 235 in 16d2339

alertChild3TextFunc().InnerHtml.Should().Be("Oh my! We got secret content3!");

and

MudBlazor/src/MudBlazor.UnitTests/State/ParameterStateUsageTests.cs

Line 250 in 16d2339

comp.Instance.Child3Instance.IsExpandedStateValue.Should().BeTrue();

aka the content must show when clicked and state should correspond that it's opened, before the fix this would fail.

How Has This Been Tested?

New bUnit tests that took me few hours to make...

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.

[ScarletKuro]

@henon I'm merging this ASAP, but just FYI and I recommend you to rebase your branches where you work on ParameterState.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.83%. Comparing base (9bb4af1) to head (16d2339).

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #8457      +/-   ##
==========================================
+ Coverage   88.76%   88.83%   +0.06%     
==========================================
  Files         416      416              
  Lines       12359    12358       -1     
  Branches     2458     2458              
==========================================
+ Hits        10971    10978       +7     
+ Misses        855      846       -9     
- Partials      533      534       +1     

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