System Certificate Access for iOS

## Feature Request

### Motivation

I have a usecase where I need to support iOS and rustls-native-certs does not work (https://github.com/hyperium/tonic/issues/1403). Using tls-webpki-roots is not a very good solution for me as I would not like to package certificates with an application, that could use the operating system certificates instead.

### Proposal

A direct support of https://github.com/rustls/rustls-platform-verifier might be able to resolve the issue. I saw that there is already a PR (https://github.com/hyperium/tonic/pull/1974) with this proposal, but it got declined. What is the status of this feature?

Is a workaround available with which it is somehow possible to inject rustls-platform-verifier on library user level in the meantime?

Relevant for https://github.com/TimOrtel/GRPC-Kotlin-Multiplatform/issues/60