Add a generic host lifetime for Windows Forms

[alex-oswald]

Enterprise customers want to keep using Windows Forms, and we want to use the generic host.

Can we add a feature to use the generic host with Windows Forms and use the lifetime of the start up form such as this library I created?

https://github.com/oswald-technologies/WindowsFormsLifetime

[alex-oswald]

@anurse I realize your team probably has other priorities than this right now, but I'm willing to help with an official implementation if acceptable.

[analogrelay]

This is certainly something that’s been on our radar. It might be something better suitable for dotnet/winforms though since it might be best for the Winforms team to own the host experience.

[analogrelay]

Triage: Moving to runtime repo in future milestone for tracking since Hosting lives in the runtime repo now. When it comes up for implementation it may be something the WinForms team should consider owning though (cc @merriemcgaw @glennc)

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