- Fixed workflows to use .NET 7 images

Use built-in System.Text.Json as a default serializer/deserializer for Json.

So that the Refit configuration would only involve IConfiguration and won't touch the
configuration services as these config is mainly involved in requesting.

Configuration will no longer use JSON and instead will use linux-style conf
file configuration like what git does.

Configuration has modes, use --set or -s flag to tell the application if
you want to set values. Use --read or -r flag to read a specific key
value or --list or -l flag to list all values set.

To reset you may use --reset flag.