Add lifetime configuration on a per-handler basis

[ksladowski]

We spoke on discord about this.

Currently the lifetime of handlers can be configured when registering them into the DI container like so:
services.AddXxxHandlers(lifetime = ServiceLifetime.Scoped)

But there is currently no way to override this setting on a per handler basis. For example, say I wanted to default my handlers to scoped but make a specific handler a transient instead. I'm imagining an argument to the attribute like [Handler(ServiceLifetime.Transient)] or something along those lines.