Pragmatic Event Sourcing with Marten using Helpdesk domain

• Simplest CQRS and Event Sourcing flow using Minimal API,
• Cutting the number of layers and boilerplate complex code to the bare minimum,
• Using all Marten helpers like WriteToAggregate and AggregateStream to simplify the processing,
• Examples of all the typical Marten's projections,
• Example of how and where to use C# Records, Nullable Reference Types, etc,
• No Aggregates. Commands are handled in the domain service as pure functions.

See more in #161.