Add support for assembly trimming and AOT

#130 added annotations for APIs that dynamically reference code (usually through reflection). These methods are, in essence, in compatible with trimming/AOT.

This means that the only available way to set up the raw Passwordless.dev SDK is by using this overload, which requires configuring the options manually:

```csharp
public static IServiceCollection AddPasswordlessSdk(
this IServiceCollection services,
Action configureOptions)
```

For the Identity integration package, we currently offer no way to add Passwordless.dev in a way that works with trimming/AOT.

Some of it may be a side-effect of the nature of ASP.NET Core as the foundation, but Microsoft is already rolling out certain alternative APIs to help support trimming/AOT scenarios. For example, for the configuration binding, we can use [this](https://andrewlock.net/exploring-the-dotnet-8-preview-using-the-new-configuration-binder-source-generator) approach to avoid reflection.

Start with the AddPasswordlessSdk overload that accepts Action and review how the Identity integration package currently registers Passwordless.dev. Read the linked .NET configuration-binder source-generator approach and assess which APIs are affected by reflection, trimming, and AOT. Done means the raw SDK and Identity integration have documented, usable setup paths that support trimming/AOT.

Written by the indexing model from the issue text.