MudDialogInstance: return back public API ForceRender

[ScarletKuro]

Description

As @mckaragoz noticed, the ForceRender was removed because of this #6563 PR
This was unintentional, as it's public API.
The StateHasChanged is made visible compared to the explicit implementation in the MudComponentBase.
This is due to the special need of such method for the DialogInstance.

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.

[codecov]

Codecov Report

Patch coverage: 50.00% and project coverage change: -0.01 ⚠️

Comparison is base (2df95f8) 91.39% compared to head (7711282) 91.38%.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #6588      +/-   ##
==========================================
- Coverage   91.39%   91.38%   -0.01%     
==========================================
  Files         397      397              
  Lines       14953    14955       +2     
==========================================
+ Hits        13666    13667       +1     
- Misses       1287     1288       +1     

Impacted Files	Coverage Δ
...lazor/Components/Dialog/MudDialogInstance.razor.cs	82.17% <50.00%> (-0.51%)	⬇️

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[henon]

Thanks. Removed the bug tag since this fixes a regression that was never released, so it doesn't need to be in the change log