Account for [noexcept] in WinMD when generating functions

[tristanlabelle]

We should be able to author WinMD components with [noexcept] and have them project into Swift without throws

[tristanlabelle]

Moved from bcny-internal bug. [noexcept] might not make sense since the method could declare itself noexcept, but in order to call it we might need to resolve an activation factory and project arguments, which might involve failable operations.

[stevenbrix]

i think this is already complete?

[stevenbrix]

swift-winrt/swiftwinrt/code_writers.h

Line 1312 in a73deec

auto maybe_throws = is_noexcept(type, method) ? "" : " throws";