Kurrent client v2 + groundwork for schema registry

[w1am]

This PR primarily introduces the Kurrent Client v2, which includes major updates and improvements to the client user experience from KurrentDB client v1.0.0 that was released this year. While initial scaffolding and setup for the schema registry have been started, the schema registry is not complete and is not fully tested.

PR includes multi append and result base pattern for all operations.

Changelist fixes DEV-853 that Includes Authorization in Empty instance of UserCredentials fixes DEV-852 to support messages with no namespaces when using MesageSchemaNameStrategy

[CLAassistant]

All committers have signed the CLA.

[linear[bot]]

DEV-853 .NET Client | Include Authorization in Empty instance

[linear[bot]]

DEV-852 .NET Client | MessageNameStrategy with no namespace should return name only