Add AutoRegisterTemplateVersion to appsettings.json configuration

[blazsvigelj]

Does this issue relate to a new feature or an existing bug?

• Bug
• New Feature

What version of Serilog.Sinks.Elasticsearch is affected? Please list the related NuGet package.
Serilog.Sinks.Elasticsearch 8.4.1

What is the target framework and operating system? See target frameworks & net standard matrix.

• netCore 2.0
• netCore 1.0
• 4.7
• 4.6.x
• 4.5.x

Please describe the current behavior?
It's not possible to specify AutoRegisterTemplateVersion in appsettings.json

Please describe the expected behavior?
It will be possible to select template version in appsettings.json.