feat: AppWindow positioning and sizing

[MartinZikmund]

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[unodevops]

🤖 Your Docs stage site is ready! Visit it here: https://unodocsprstaging.z13.web.core.windows.net/pr-16535/index.html

[unodevops]

🤖 Your Docs stage site is ready! Visit it here: https://unodocsprstaging.z13.web.core.windows.net/pr-16535/index.html

[unodevops]

🤖 Your WebAssembly Sample App stage site is ready! Visit it here: https://unowasmprstaging.z20.web.core.windows.net/pr-16535/index.html