Lazy Load Command Handlers

[robinmanuelthiel]

Currently, the ScheduledCommandRunner instantiates all Command Handlers, independent of if it is used at all. This should only be needed, when a command is actually getting processed, so we should lazy load the Handlers.

This can become a problem, when all Command Handlers of a project across multiple micro-services are shared in one assembly, which can lead to Command Handlers being loaded, that have dependencies to stuff that is not available in the current context.

[robinmanuelthiel]

I vote for explicitly defining the command handlers that should be loaded in the DI (even lazy) because I only catch lazy loaded dependencies that cannot be resolved in the dependency chain at runtime...