When we implemented support for using default interface members for binding protocols, we also unintentionally introduced a size regression. This happened because we now tell the linker to keep all methods in a protocol interface, thus all the corresponding types end up marked as well, etc.
This had an additional side effect: depending on the types that weren't linked away anymore, the App Store could flag an app, saying that additional entitlements is needed. This is what's happening in #21002: the App Store detects that the app references the `application:didRegisterForRemoteNotificationsWithDeviceToken:` selector [1] (from the method `RegisteredForRemoteNotifications` on `IUIApplicationDelegate`) and tells the developer they probably need the push notification entitlement.
The good news is that we don't need these protocol interface methods at runtime if the optimization to register protocols with the static registrar is enabled (which it is by default).
In this PR I teach the optimizer to remove the DynamicDependency attributes keeping these protocol interface methods from being trimmed out.
## Size improvements
* monotouch-test build for Release/ios-arm64 shrinks by [2.9mb (-2.6%)](https://gist.github.com/rolfbjarne/5e8ca6ea6854dc4a46f8e838dff11e6b)
* A very simple app (tests/dotnet/MySimpleApp) shrinks by [176kb (-0.3%)](https://gist.github.com/rolfbjarne/f0e062900528eb499fd96d124d18376f)
[1]: This is somewhat speculative, but it's probably not far from what the App Store actually does.
Fixes#21002.
ff707c145e