Extend the client area when a Win32 window is opened in maximised state

[TomEdwardsEnscape]

#16029 fixed the internal show/hide state not being updated when a window opens in a maximised state, but it didn't extend the client area in the same circumstances. This PR adds the required calls.

Breaking changes

None

Obsoletions / Deprecations

None

Fixed issues

Fixes #16503

[maxkatz6]

Do you think it would be difficult to add an integrational test for this case?
https://github.com/AvaloniaUI/Avalonia/blob/master/tests/Avalonia.IntegrationTests.Appium/WindowDecorationsTests.cs

I assume PInvoke to get current actual window position would be needed as well.

On how to run these tests https://github.com/AvaloniaUI/Avalonia/tree/master/tests/Avalonia.IntegrationTests.Appium

[TomEdwardsEnscape]

I'm not in a position to set that system up on my computer. It would also be difficult for me because I've never used Appium. I'll happily push changes made by someone else to this branch though.

[avaloniaui-bot]

You can test this PR using the following package version. 11.2.999-cibuild0050949-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]