Support for std::span for winrt::array_view and winrt::com_array

[jonwis]

This fixes #1289 per "option C" by completing what #1331 started.

• Constructors for both array_view and com_array that take a span
• Conversions on both array_view and com_array that produce a span
• Tests for the conversions and constructions
• Additional ctad support for easy use

@JaiganeshKumaran thank you for the initial start - see if this meets your needs, please.

[kennykerr]

Hopefully @DefaultRyan can spare a few minutes to look this over. He probably has the best handle on the standard library best practices.

[kennykerr]

I still think the lifetime here is bonkers, but admittedly not any worse than the C++ standard library.

[dmachaj]

Sorry I'm a little late to the party. Do these new methods affect vtable layout at all? In other words, does span support need an ODR pragma to prevent mismatches?

[kennykerr]

Do these new methods affect vtable layout at all?

std::span is not an ABI type.

[jonwis]

It's pure conversion methods; no change to the layout or functionality of array_view or com_array here.