Update to .NET8.0 and update Nuget packages

[canro91]

This PR updates the target framework to .NET8.0. Also, it updates all Nuget packages and fixes breaking changes.

• Remove deprecated MediatR.Extensions.Microsoft.DependencyInjection
• Update Ardalis.Endpoint and fix breaking changes
  • BaseAsyncEndpoint was renamed to EndpointBaseAsync
• Update SharedKernel and fix breaking changes
  • IApplicationEvent was renamed to BaseIntegrationEvent
• Update Ardalis.HttpClientTestExtensions
  • GetAndDeserialize was renamed to GetAndDeserializedAsync
• Change MediatR registration with Autofac.
  • See: https://stackoverflow.com/a/75677259
• Fix broken unit tests

Relates to: #68 Addresses: #66 #67