Create `til` namespaces shorthanding the chromium safe math

[miniksa]

We may actually want to namespace a bunch of this stuff into til (with using), more than what @lhecker's already suggested. It'll make us more robust if we ever do want to change things up in the future, and avoid littering chromium::numerics::whatever all over every part of the code.

Originally posted by @DHowett-MSFT in #4144 (comment)

This represents putting something like til::saturated<T> as the shorthand for the chromium::numerics::ClampedNumeric<T> and so forth for the other representations per @DHowett-MSFT's comment.

[DHowett-MSFT]

We may have decided we don't need to do this, actually. The namespace isn't all that bad. I don't recall, though.

[zadjii-msft]

Hey @miniksa @DHowett, it's been two years of this and I don't think this is bothering anyone. Close?

[miniksa]

@lhecker, as the current master of the til namespace, what's your opinion here?