Hot reload: Update RuntimeTypeMetadataUpdateHandler to use a QCall to clear reflection caches #50938
Description
#51242 updated Corelib to clear reflection caches, but it does so using managed code to iterate through all types. This has some deficiencies, as noted in a TODO in the code:
// TODO: This should ideally be in a QCall in the runtime. As written here:
// - This materializes all types in the app, creating RuntimeTypes for them.
// - This force loads all assembly dependencies, which might not work well for packages that may depend on resolve events firing at the right moment.
// - This does not cover instantiated generic types.