Add LoggerMessage.Define overloads for 0, 4, 5, and 6 args

[victorhurdugaci]

Please add a non generic version of LoggerMessage.Define because there are cases in which the logged message doesn't have any parameters

[kichalla]

Ideally using Define is not required in the case where you are not using a message format string and do not have any parameters to pass. Define was optimized for these cases for perf reasons.

That said, we currently have an extension for DefineScope which does not take in any arguments...probably this should be removed to keep it consistent with Define @rynowak
https://github.com/aspnet/Logging/blob/dev/src/Microsoft.Extensions.Logging.Abstractions/LoggerMessage.cs#L20

[Eilon]

We should have overloads for: no parameters, and also need to add overloads for 4, 5, and 6 args.