[mdspan] Add new port for kokkos/mdspan

[jdthomas]

Adds new port for mdspan

• What does your PR fix?

  Fixes [New Port Request] mdspan #21183 , adds new port for mdspan

• Which triplets are supported/not supported? Have you updated the CI baseline?

  all, No

• Does your PR follow the maintainer guide?

  Yes

• If you have added/updated a port: Have you run ./vcpkg x-add-version --all and committed the result?

  Yes

[ghost]

All CLA requirements met.

[NancyLi1013]

LGTM, thanks for adding this port. @jdthomas

[crtrott]

@jdthomas I haven't ever used vcpkg would it be possible to get some guidance on how we can make sure we don't break this integration?

[jdthomas]

@jdthomas I haven't ever used vcpkg would it be possible to get some guidance on how we can make sure we don't break this integration?

@crtrott
heh, I am new to this as well, so maybe there's someone better to answer any specific question :)
In the vcpkg repo there's a hard coded sha (aced2cebd362a1e15830da030bd16748131d28bd) that it pulls from the mdspan repo. I think the only maintenance you might be interested in is potentially updating that if mdspan gets updates. Since mdspan takes no external dependencies, I cannot imagine there being any breakage other than potentially while updating (and even then super unlikely unless someone adds another "port" that depends on mdspan). ... but again, i am new to this too 🤷🏽‍♀️