Use Aspect Provider instead of Concrete Aspect Target

[SentryMan]

• Changed generated aspect proxy class to use AspectProvider Interface
• Changed Aspect Annotation to only accept types extending AspectProvider.
• Removed unused fields in generated proxy class

Example generated proxy class:

Before:

@Proxy
@Generated("io.avaje.inject.generator")
public final class ServiceClass$Proxy extends ServiceClass {

  private final TimedAspect timedAspect;

  private Method callDownStream0;
  private MethodInterceptor callDownStream0Timed;

  public ServiceClass$Proxy(TimedAspect timedAspect, ApiClient api) {
    super(api);
    this.timedAspect = timedAspect;
    try {
      callDownStream0 = ServiceClass.class.getDeclaredMethod("callDownStream");
      callDownStream0Timed = timedAspect.interceptor(callDownStream0, callDownStream0.getAnnotation(Timed.class));

    } catch (Exception e) {
      throw new IllegalStateException(e);
    }
  }

  @Override
  public byte[] callDownStream() {
    var call = new Invocation.Call<>(() -> super.callDownStream())
      .with(this, callDownStream0);
    try {
      callDownStream0Timed.invoke(call);
      return call.finalResult();
    } catch (InvocationException e) {
      throw e;
    } catch (Throwable e) {
      throw new InvocationException(e);
    }
  }
}

After:

@Proxy
@Generated("io.avaje.inject.generator")
public final class ServiceClass$Proxy extends ServiceClass {

  private Method callDownStream0;
  private MethodInterceptor callDownStream0Timed;

  public ServiceClass$Proxy(AspectProvider<Timed> timed, ApiClient api) {
    super(api);
    try {
      callDownStream0 = ServiceClass.class.getDeclaredMethod("callDownStream");
      callDownStream0Timed = timed.interceptor(callDownStream0, callDownStream0.getAnnotation(Timed.class));
    } catch (Exception e) {
      throw new IllegalStateException(e);
    }
  }

  @Override
  public byte[] callDownStream() {
    var call = new Invocation.Call<>(() -> super.callDownStream())
      .with(this, callDownStream0);
    try {
      callDownStream0Timed.invoke(call);
      return call.finalResult();
    } catch (InvocationException e) {
      throw e;
    } catch (Throwable e) {
      throw new InvocationException(e);
    }
  }
}